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Direct inhibition of endothelial nitric oxide synthase by hydrogen sulfide: Contribution to dual modulation of vascular tension
Abstract
We characterized actions of hydrogen sulfide (H(2)S) on tension of isolated rat and mouse aortae, and then examined if H(2)S could directly modulate activity of endothelial nitric oxide (NO) synthase (eNOS). Isometric tension was recorded in rat and mouse aortic rings. Activity of recombinant bovine eNOS was determined as conversion of [(3)H]-arginine into [(3)H]-citrulline. NaHS, a H(2)S donor, caused contraction at low concentrations and relaxation at high concentrations in both rat and mouse aortae precontracted with phenylephrine. The contractile and relaxant effects of NaHS were enhanced and partially blocked, respectively, by the K(+)(ATP) channel inhibitor glibenclamide in the rat, but not mouse, aortae. In the KCl-precontracted rat aorta, NaHS produced glibenclamide-resistant contraction and relaxation. NaHS produced only relaxation, but not contraction, in the endothelium-denuded aortae, and also in the endothelium-intact aortae in the presence of inhibitors of NOS or soluble guanylate cyclase. NaHS pretreatment greatly attenuated the relaxation induced by acetylcholine, but not by an NO donor, in the tissues. Finally, we found that NaHS inhibited the conversion of [(3)H]-arginine into [(3)H]-citrulline by recombinant eNOS. NaHS thus causes contraction and relaxation in rat and mouse aortae. K(+)(ATP) channels are considered to contribute only partially to the NaHS-evoked relaxation. Most interestingly, our data demonstrate direct inhibition of eNOS by NaHS, probably responsible for its contractile activity, being evidence for a novel function of H(2)S.
... For example, although H 2 S has often been reported as an inhibitor of the LTCC, it can also activate the LTCC. [36,37] Similarly, H 2 S has been demonstrated to inhibit endothelial NO synthase [38,6] and stimulate the release of endothelial NO. [38,6] As will be discussed, these discrepant results may be explained by considering whether the effector was H 2 S or its redox cousin HS • . Similar to what was previously demonstrated for other redox cousins (HNO and O 2 ...
... For example, although H 2 S has often been reported as an inhibitor of the LTCC, it can also activate the LTCC. [36,37] Similarly, H 2 S has been demonstrated to inhibit endothelial NO synthase [38,6] and stimulate the release of endothelial NO. [38,6] As will be discussed, these discrepant results may be explained by considering whether the effector was H 2 S or its redox cousin HS • . Similar to what was previously demonstrated for other redox cousins (HNO and O 2 ...
... Further studies are needed to test uncertainties, such as whether pulmonary and systemic arteries utilize distinct routes for O 2 handling/ROS production [46,47] and thus different RSSs [19] and whether the inhibition of H 2 S oxidation results in the widely reported transition of H 2 S-induced vasoconstriction to vasodilation at higher H 2 S levels. [5][6][7][8] ...
Although the gasotransmitter hydrogen sulfide (H2S) is well known for its vasodilatory effects, H2S also exhibits vasoconstricting properties. Herein, it is demonstrated that administration of H2S as intravenous sodium sulfide (Na2S) increased blood pressure in sheep and rats, and this effect persisted after H2S has disappeared from the blood. Inhibition of the L‐type calcium channel (LTCC) diminished the hypertensive effects. Incubation of Na2S with whole blood, red blood cells, methemoglobin, or oxyhemoglobin produced a hypertensive product of H2S, which is not hydrogen thioperoxide, metHb‐SH⁻ complexes, per‐/poly‐ sulfides, or thiolsulfate, but rather a labile intermediate. One‐electron oxidation of H2S by oxyhemoglobin generated its redox cousin, sulfhydryl radical (HS•). Consistent with the role of HS• as the hypertensive intermediate, scavenging HS• inhibited Na2S‐induced vasoconstriction and activation of LTCCs. In conclusion, H2S causes vasoconstriction that is dependent on the activation of LTCCs and generation of HS• by oxyhemoglobin.
... In the battle of the interchangeable production of H 2 S and NO, another finding cropped up, supporting the claim that H 2 S is responsible for the direct inhibition of endothelial nitric oxide synthase (eNOS). [46] Inhibit block synthesis NO eNOS NO H 2 S Endothelial nitric oxide synthase is responsible for the production of NO in endothelial cells. This theory is born out of the result of the first school of thought, which proposed that NO can potentiate the response of H 2 S, but NO can do this. ...
... This theory is born out of the result of the first school of thought, which proposed that NO can potentiate the response of H 2 S, but NO can do this. [46] has elaborated that H 2 S is responsible for the inhibition of eNOS, as well as iNOS and nNOS. They further strengthened the results of their study by explaining that H 2 S and tetrahydrobiopterin (BH 4 ) reverse the H 2 S inhibition of eNOS and nNOS, but not iNOS. ...
... The cardioprotective response of the NOS family mentioned in [50,51] is contrary to the results by. [46] Another area of interest is the formation of the intermediate complex nitrosothiol, which is responsible for the vasorelaxant effect in the blood vessels through interaction between two gasotransmitters, H 2 S and NO. [23,45] The presence of this intermediate molecule, nitrosothiol, has not been fully confirmed and has been considered as a possible molecule for the said action. ...
... During the debate regarding this interchangeable production of H2S and NO, another study illustrated that H2S was responsible for the direct inhibition of eNOS [131] (Figure 3) and that it was In this section, this review article focuses on the interaction of H 2 S and NO. Each has been observed to stimulate the synthesis of the other and proposed as a surrogate marker for production of the other. ...
... During the debate regarding this interchangeable production of H 2 S and NO, another study illustrated that H 2 S was responsible for the direct inhibition of eNOS [131] (Figure 3) and that it was responsible for the production of NO in endothelial cells. In later work, Kubo et al. [131] elaborated that H 2 S was not only responsible for inhibition of eNOS but also iNOS and nNOS. ...
... During the debate regarding this interchangeable production of H 2 S and NO, another study illustrated that H 2 S was responsible for the direct inhibition of eNOS [131] (Figure 3) and that it was responsible for the production of NO in endothelial cells. In later work, Kubo et al. [131] elaborated that H 2 S was not only responsible for inhibition of eNOS but also iNOS and nNOS. ...
... High concentration of H 2 S (> 700 ppm or 2 0000 µM) is acutely lethal in both human and animals [12]. Circulating levels of H 2 S are ~ 50 μM in both humans and animals [9, 13] while its concentrations in mammalian tissues were reported to range between 50-160 μM [9,14]. Sulfan sulfur is the major storage pool of H 2 S [9]. ...
... Cystathionine-γ-lyase (CSE) 4.4.1.1 Cytosol Cardiovascular system (heart, aorta, mesenteric artery, pulmonary artery, and portal vein) [9,20,40,41], small intestine [9,14,20], stomach [9], liver [9,20,41], kidney [9,20,41], uterus [20], brain [20], pancreatic islets [20], placenta [20], penile tissue [20] Cystathionine-β-synthetase (CBS) ...
... Brain [14,20,40,41], CNS [9], liver [9,20], kidney [9,20], pancreatic islets [20], ileum [20], uterus [20], placenta [20], not detectable in the blood vessels [40], penile tissue [20] Enzymes ...
... However, there is still no clarity about the nature of the interaction [7,130]. H 2 S and NO can affect not only the generation of each other through enzymatic expression and activity but also the further downstream signaling pathway [131][132][133]. The next part will provide current understanding of the interactions and mechanisms between H 2 S and NO in the cardiovascular system. ...
... H 2 S directly inhibited the activity of recombinant eNOS to cause the increase of aortic contractility. However, the natural mechanism is not clear [132]. In the model of myocarditis, there were high iNOS mRNA and protein expression. ...
... However, the other labs reported some conflicting results. Kubo et al. showed that the activity of eNOS was inhibited by H 2 S in rat and mouse aortic rings [132]. In addition, Geng et al. found that both exogenous and endogenous H 2 S reduced NO generation and prevented eNOS activity and transcription [165]. ...
Hydrogen sulfide (H 2 S) and nitric oxide (NO) are now recognized as important regulators in the cardiovascular system, although they were historically considered as toxic gases. As gaseous transmitters, H 2 S and NO share a wide range of physical properties and physiological functions: they penetrate into the membrane freely; they are endogenously produced by special enzymes, they stimulate endothelial cell angiogenesis, they regulate vascular tone, they protect against heart injury, and they regulate target protein activity via posttranslational modification. Growing evidence has determined that these two gases are not independent regulators but have substantial overlapping pathophysiological functions and signaling transduction pathways. H 2 S and NO not only affect each other’s biosynthesis but also produce novel species through chemical interaction. They play a regulatory role in the cardiovascular system involving similar signaling mechanisms or molecular targets. However, the natural precise mechanism of the interactions between H 2 S and NO remains unclear. In this review, we discuss the current understanding of individual and interactive regulatory functions of H 2 S and NO in biosynthesis, angiogenesis, vascular one, cardioprotection, and posttranslational modification, indicating the importance of their cross-talk in the cardiovascular system.
... During the debate regarding this interchangeable production of H2S and NO, another study illustrated that H2S was responsible for the direct inhibition of eNOS [131] (Figure 3) and that it was In this section, this review article focuses on the interaction of H 2 S and NO. Each has been observed to stimulate the synthesis of the other and proposed as a surrogate marker for production of the other. ...
... During the debate regarding this interchangeable production of H 2 S and NO, another study illustrated that H 2 S was responsible for the direct inhibition of eNOS [131] (Figure 3) and that it was responsible for the production of NO in endothelial cells. In later work, Kubo et al. [131] elaborated that H 2 S was not only responsible for inhibition of eNOS but also iNOS and nNOS. ...
... During the debate regarding this interchangeable production of H 2 S and NO, another study illustrated that H 2 S was responsible for the direct inhibition of eNOS [131] (Figure 3) and that it was responsible for the production of NO in endothelial cells. In later work, Kubo et al. [131] elaborated that H 2 S was not only responsible for inhibition of eNOS but also iNOS and nNOS. ...
The gasotransmitters are a family of gaseous signaling molecules which are produced endogenously and act at specific receptors to play imperative roles in physiologic and pathophysiologic processes. As a well-known gasotransmitter along with hydrogen sulfide and carbon monoxide, nitric oxide (NO) has earned repute as a potent vasodilator also known as endothelium-derived vasorelaxant factor (EDRF). NO has been studied in greater detail, from its synthesis and mechanism of action to its physiologic, pathologic, and pharmacologic roles in different disease states. Different animal models have been applied to investigate the beneficial effects of NO as an antihypertensive, renoprotective, and antihypertrophic agent. NO and its interaction with different systems like the renin–angiotensin system, sympathetic nervous system, and other gaseous transmitters like hydrogen sulfide are also well studied. However, links that appear to exist between the endocannabinoid (EC) and NO systems remain to be fully explored. Experimental approaches using modulators of its synthesis including substrate, donors, and inhibitors of the synthesis of NO will be useful for establishing the relationship between the NO and EC systems in the cardiovascular and renal systems. Being a potent vasodilator, NO may be unique among therapeutic options for management of hypertension and resulting renal disease and left ventricular hypertrophy. Inclusion of NO modulators in clinical practice may be useful not only as curatives for particular diseases but also for arresting disease prognoses through its interactions with other systems.
... H 2 S exerts biphasic effect on vascular tissue and produces vasoconstriction at lower concentrations (10-100 μM of NaSH yields ∼3-30 μM H 2 S) in rat aorta [10,186] or 30-100 μM of H 2 S in rat and mouse aortae [4] and vasorelaxation at higher concentrations, i.e. > 60 μM [7,158,186]; in physiological solutions, about one-third of NaSH exists as H 2 S [186]. It has been argued that contractile activity of H 2 S on blood vessels, which needs lower concentrations, is physiologically more important than its relaxant activity, which needs higher concentrations [187]. H 2 S-induced vasoconstriction may be due to NO quenching [7] or inactivation [158]/inhibition of eNOS [7], and NOindependent mechanisms [94] including lowering cyclic adenosine monophosphate (cAMP) levels in VSM cells at high concentrations [94]. ...
... Contractile activity of H 2 S in phenylephrine-precontracted rat aorta disappeared after endothelium removal, NOS inhibition, or sGC inhibition [4]. Contractile effect of H 2 S is endothelium-dependent [10] and involves the NO-cGMP pathway [187]. In addition, H 2 S reduces acetylcholine-induced relaxation but not sodium nitroprusside (SNP)induced relaxation [187]. ...
... Contractile effect of H 2 S is endothelium-dependent [10] and involves the NO-cGMP pathway [187]. In addition, H 2 S reduces acetylcholine-induced relaxation but not sodium nitroprusside (SNP)induced relaxation [187]. H 2 S at 30-3000 μM inhibits eNOS activity in a concentration-dependent manner, which contributes to its vasoconstrictor activity [187]. ...
Nitric oxide (NO) and hydrogen sulfide (H2S) are two gasotransmitters that are produced in the vasculature and contribute to the regulation of vascular tone. NO and H2S are synthesized in both vascular smooth muscle and endothelial cells; NO functions primarily through the sGC/cGMP pathway, and H2S mainly through activation of the ATP-dependent potassium channels; both leading to relaxation of vascular smooth muscle cells. A deficit in the NO/H2S homeostasis is involved in the pathogenesis of various cardiovascular diseases, especially hypertension. It is now becoming increasingly clear that there are important interactions between NO and H2S and that have a profound impact onvascular tone and this may provide insights into the new therapeutic interventions. The aim of this review is to provide a better understanding of individual and interactive roles of NO and H2S in vascular biology. Overall, available data indicate that both NO and H2S contribute in vascular (patho)physiology and in regulating blood pressure. In addition, boosting NO and H2S using various dietary sources or donors could be a hopeful therapeutic strategy in the management of hypertension.
... The opposing findings may result from methodological differences, including the timeline for measurement of the effects, release kinetics of the donor molecules, and concentrations used. For instance, H 2 S has biphasic effects on the vasculature, causing vasoconstriction at low concentrations and vasorelaxation at higher concentrations [409,410]. Thus, consistency across experiments would be crucial for evaluating the trends and potential application within COVID-19 management. ...
... Based on these studies, exogenous H 2 S administration to restore both H 2 S and eNOS-derived NO holds double promise for combatting extensive endothelial dysfunction and the resulting thrombotic complications that may arise in severe COVID-19. Yet there is also some evidence that suggests H 2 S inhibits eNOS [410,423]. The dual effects of H 2 S on vascular tone may be due to the biphasic actions of H 2 S. ...
Viral infections are a continuing global burden on the human population, underscored by the ramifications of the COVID-19 pandemic. Current treatment options and supportive therapies for many viral infections are relatively limited, indicating a need for alternative therapeutic approaches. Virus-induced damage occurs through direct infection of host cells and inflammation-related changes. Severe cases of certain viral infections, including COVID-19, can lead to a hyperinflammatory response termed cytokine storm, resulting in extensive endothelial damage, thrombosis, respiratory failure, and death. Therapies targeting these complications are crucial in addition to antiviral therapies. Nitric oxide and hydrogen sulfide are two endogenous gasotransmitters that have emerged as key signaling molecules with a broad range of antiviral actions in addition to having anti-inflammatory properties and protective functions in the vasculature and respiratory systems. The enhancement of endogenous nitric oxide and hydrogen sulfide levels thus holds promise for managing both early-stage and later-stage viral infections, including SARS-CoV-2. Using SARS-CoV-2 as a model for similar viral infections, here we explore the current evidence regarding nitric oxide and hydrogen sulfide's use to limit viral infection, resolve inflammation, and reduce vascular and pulmonary damage.
... The authors confirmed that pretreatment with an H 2 S donor potentiated the vasorelaxant response of the thoracic aorta to acetylcholine and to an NO donor and increased cGMP levels. On the other hand, Kubo et al. [7] showed that the H 2 S donor induced the inhibition of endothelial NO-synthase (eNOS) activity in the arterial walls of rat and mouse aortas and that this effect was associated with an increase in arterial tension. Moreover, antioxidant effects of H 2 S that could be mediated through transcription factors such as Nrf2 and nuclear factor-κB were observed. ...
... Recently, Szijártó et al. [47] demonstrated that one of the major functions of H 2 S produced by CSE is to reduce endothelial NO bioavailability by the direct interaction of H 2 S and NO. Similarly, Kubo et al. [7] showed that H 2 S induced the inhibition of NOS activity in the arterial walls of rat and mouse aortas, and Geng et al. [48] showed that low doses of H 2 S donor downregulated the L-arginine/NO pathway by inhibiting eNOS expression and by decreasing NOS activity. Based on the findings, we hypothesize that H 2 S produced by the arterial wall and PVAT of HTG rats could inhibit residual NO signaling, leading to the attenuation of vasorelaxation. ...
The aim of this study was to evaluate the mutual relationship among perivascular adipose tissue (PVAT) and endogenous and exogenous H 2 S in vasoactive responses of isolated arteries from adult normotensive (Wistar) rats and hypertriglyceridemic (HTG) rats, which are a nonobese model of metabolic syndrome. In HTG rats, mild hypertension was associated with glucose intolerance, dyslipidemia, increased amount of retroperitoneal fat, increased arterial contractility, and endothelial dysfunction associated with arterial wall injury, which was accompanied by decreased nitric oxide (NO)-synthase activity, increased expression of H 2 S producing enzyme, and an altered oxidative state. In HTG, endogenous H 2 S participated in the inhibition of endothelium-dependent vasorelaxation regardless of PVAT presence; on the other hand, aortas with preserved PVAT revealed a stronger anticontractile effect mediated at least partially by H 2 S. Although we observed a higher vasorelax-ation induced by exogenous H 2 S donor in HTG rats than in Wistar rats, intact PVAT subtilized this effect. We demonstrate that, in HTG rats, endogenous H 2 S could manifest a dual effect depending on the type of triggered signaling pathway. H 2 S within the arterial wall contributes to endothelial dys-function. On the other hand, PVAT of HTG is endowed with compensatory vasoactive mechanisms, which include stronger anti-contractile action of H 2 S. Nevertheless, the possible negative impact of PVAT during hypertriglyceridemia on the activity of exogenous H 2 S donors needs to be taken into consideration.
... 103 Low concentrations of NaHS induced contraction of aorta from mice/rats. 104 The molecular pathways involved in H 2 S-induced vascular contraction were found to be related to decreasing nitric oxide (NO) bioavailability by converting NO to an inactive nitrosothiol and N-nitrosohydroxylamine-Nsulfonate or directly reducing NO production, 83,[103][104][105] or down-regulation of cAMP endotheliumindependently. 106 The pathophysiological importance of low concentration of H 2 S-mediated vascular constriction has been suggested for further investigation. ...
... 103 Low concentrations of NaHS induced contraction of aorta from mice/rats. 104 The molecular pathways involved in H 2 S-induced vascular contraction were found to be related to decreasing nitric oxide (NO) bioavailability by converting NO to an inactive nitrosothiol and N-nitrosohydroxylamine-Nsulfonate or directly reducing NO production, 83,[103][104][105] or down-regulation of cAMP endotheliumindependently. 106 The pathophysiological importance of low concentration of H 2 S-mediated vascular constriction has been suggested for further investigation. ...
Diabetes is one of the most prevalent metabolic disorders and is estimated to affect 400 million of 4.4% of population worldwide in the next 20 year. In diabetes, risk to develop vascular diseases is two-to four-fold increased. Ischemic tissue injury, such as refractory wounds and critical ischemic limb (CLI) are major ischemic vascular complications in diabetic patients where oxygen supplement is insufficient due to impaired angiogenesis/neovascularization. In spite of intensive studies, the underlying mechanisms of diabetes-impaired ischemic tissue injury remain incompletely understood. Hydrogen sulfide (H2S) has been considered as a third gasotransmitter regulating angiogenesis under physiological and ischemic conditions. Here, the underlying mechanisms of insufficient H2S-impaired angiogenesis and ischemic tissue repair in diabetes are discussed. We will primarily focuses on the signaling pathways of H2S in controlling endothelial function/biology, angiogenesis and ischemic tissue repair in diabetic animal models. We summarized that H2S plays an important role in maintaining endothelial function/biology and angiogenic property in diabetes. We demonstrated that exogenous H2S could be a potential agent for therapeutics of endothelial dysfunction and ischemic tissue repair in diabetes.
... Если в сердечно-сосудистой системе H 2 S ингибирует пролиферацию гладкомышечных клеток (ГМК), модулируя МАРК-киназный сигнальный путь, и эффективно расслабляет гладкие мышцы кишечника, интактные и деэндотелизированные сосудистые сегменты за счет активации АТФ-чувствительных, Са 2+ -зависимых и (или) потенциалзависимых аминопиридинчувствительных калиевых каналов [15,20], то далеко не ясен механизм его влияния на другие ГМК. Например, по данным S. Kubo, сероводород может вызывать и сокращение сегментов аорты крысы через изменение внутриклеточной концентрации циклического аденозинмонофосфата (цАМФ) или активацию Cl -/НСО -3 -обменника и ацидификацию цитоплазмы [15]. ...
... Если в сердечно-сосудистой системе H 2 S ингибирует пролиферацию гладкомышечных клеток (ГМК), модулируя МАРК-киназный сигнальный путь, и эффективно расслабляет гладкие мышцы кишечника, интактные и деэндотелизированные сосудистые сегменты за счет активации АТФ-чувствительных, Са 2+ -зависимых и (или) потенциалзависимых аминопиридинчувствительных калиевых каналов [15,20], то далеко не ясен механизм его влияния на другие ГМК. Например, по данным S. Kubo, сероводород может вызывать и сокращение сегментов аорты крысы через изменение внутриклеточной концентрации циклического аденозинмонофосфата (цАМФ) или активацию Cl -/НСО -3 -обменника и ацидификацию цитоплазмы [15]. ...
... It targets ion channels as well as signaling molecules and transcription factors. Indeed, by sulfhydration of K ATP channels in smooth muscle cells, H 2 S prompted vasorelaxation [28] and bronchodilation [29]. H 2 S is also involved in MAPKs' activation, which results in the increase of the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) and protein kinase C levels with the following inhibition of pro-inflammatory cytokines effects [30,31]. ...
... Moreover, H 2 S activates the eNOS/NO/P-38 MAPK pathway to prevent ischemia-reperfusion injury [42] In contrast, H 2 S seems to inhibit all NOS isoforms [43]. Likewise, both in in vitro and in vivo models H 2 S is able to downregulate the vascular L-arginine/NOS/NO pathway [29]. Consistently, it has been reported that H 2 S reduced pulmonary vascular remodeling by downregulating eNOS protein expression and activity [44]. ...
Nitric Oxide (NO) is internationally regarded as a signal molecule involved in several functions in the respiratory tract under physiological and pathogenic conditions. Hydrogen Sulfide (H2S) has also recently been recognized as a new gasotransmitter with a diverse range of functions similar to those of NO.
Depending on their respective concentrations, both these molecules act synergistically or antagonistically as signals or damage promoters. Nevertheless, available evidence shows that the complex biological connections between NO and H2S involve multiple pathways and depend on the site of action in the respiratory tract, as well as on experimental conditions. This review will provide an update on these two gasotransmitters in physiological and pathological processes.
... H 2 S can activate ATP-sensitive K + channels (K ATP ) in smooth muscle to induce vasodilation in the blood vessel (Zhao et al. 2001). Kubo et al. (2007) also have shown sodium hydrosulfide (NaHS), a H 2 S donor, causes relaxation of aorta in rat and mouse while the relaxation effect of NaHS is partially mediated by K ATP channels (Kubo et al. 2007). Moreover, H 2 S can regulate Ca 2+ homeostasis of human vascular endothelial, suggesting that H 2 S may Vol. ...
... H 2 S can activate ATP-sensitive K + channels (K ATP ) in smooth muscle to induce vasodilation in the blood vessel (Zhao et al. 2001). Kubo et al. (2007) also have shown sodium hydrosulfide (NaHS), a H 2 S donor, causes relaxation of aorta in rat and mouse while the relaxation effect of NaHS is partially mediated by K ATP channels (Kubo et al. 2007). Moreover, H 2 S can regulate Ca 2+ homeostasis of human vascular endothelial, suggesting that H 2 S may Vol. ...
The purpose of the present study was to define the indirect central effect of hydrogen sulfide (H2S) on baroreflex control of sympathetic outflow. Perfusing the isolated carotid sinus with sodium hydrosulfide (NaHS), a H2S donor, the effect of H2S was measured by recording changes of renal sympathetic nerve activity (RSNA) in anesthetized male rats. Perfusion of isolated carotid sinus with NaHS (25, 50, 100 μmol/l) dose and time-dependently inhibited sympathetic outflow. Preconditioning of glibenclamide (20 µmol/l), a ATP-sensitive K+ channels (KATP) blocker, the above effect of NaHS was removed. With 1, 4-dihydro-2, 6-dimethyl-5-nitro-4-(2-[trifluoromethyl] phenyl) pyridine-3-carboxylic acid methyl ester (Bay K8644, 500 nmol/l) pretreatment, which is an agonist of L-calcium channels, the effect of NaHS was eliminated. Perfusion of cystathionine γ-lyase (CSE) inhibitor, DL-propargylglycine (PPG, 200 μmol/l), increased sympathetic outflow. The results show that exogenous H2S in the carotid sinus inhibits sympathetic outflow. The effect of H2S is attributed to opening KATP channels and closing the L-calcium channels.
... H 2 S-increased [Ca 2+ ] i is mediated through increasing IP 3 -dependent intracellular Ca 2+ mobilization, activating K ATP channels, and favoring the reverse mode of Na + -Ca 2+ exchanger [1,17,101]. Inhibitory effect of NaSH on eNOS is concentration dependent with an IC 50 of 170 μM [4]; which is due to the inhibition of BH 4 function [282] and decreasing the phospho-eNOS (serine 1177) [283]. ...
... Effect of NO on H 2 S synthesis is also not straightforward. It has been reported that NO increases the activity and expression of CSE [93,102,282,284,285], has no effect on H 2 Sproducing enzymes [286], or even directly inhibits CSE activity in vitro with an IC 50 of about 100 nM [95]. NO-increased H 2 S synthesis is mediated by cGMP as it is reduced by inhibition of sGC [287]. ...
Nitric oxide (NO) and hydrogen sulfide (H2S) are two gasotransmitters that are produced in the human body and have a key role in many of the physiological activities of the various organ systems. Decreased NO bioavailability and deficiency of H2S are involved in the pathophysiology of type 2 diabetes and its complications. Restoration of NO levels have favorable metabolic effects in diabetes. The role of H2S in pathophysiology of diabetes is however controversial; H2S production is decreased during development of obesity, diabetes, and its complications, suggesting the potential therapeutic effects of H2S. On the other hand, increased H2S levels disturb the pancreatic β-cell function and decrease insulin secretion. In addition, there appear to be important interactions between NO and H2S at the levels of both biosynthesis and signaling pathways, yet clear an insight into this relationship is lacking. H2S potentiates the effects of NO in the cardiovascular system as well as NO release from its storage pools. Likewise, NO increases the activity and the expression of H2S-generating enzymes. Inhibition of NO production leads to elimination/attenuation of the cardioprotective effects of H2S. Regarding the increasing interest in the therapeutic applications of NO or H2S-releasing molecules in a variety of diseases, particularly in the cardiovascular disorders, much is to be learned about their function in glucose/insulin metabolism, especially in diabetes. The aim of this review is to provide a better understanding of the individual and the interactive roles of NO and H2S in carbohydrate metabolism.
... In rat conduit arteries, vasoconstrictor and vasorelaxant effects have both been demonstrated (6). Whereas NO-independent pathways, predominantly K ATP activation, are responsible for the vasorelaxing effects of H 2 S, the vasoconstrictor effects of H 2 S are likely related to downregulation of the L-arginine/NO pathway (3,7). Nevertheless, contradictory results regarding the synergistic and antagonistic effects of H 2 S and NO have been published. ...
... As mentioned above, we confirmed a loss of endogenous CSE-generated H 2 S in SHR compared to Wistar rats. Low concentrations of H 2 S were found to induce the down-regulation of L-arginine/NO pathway in both cultured and isolated vascular tissues via several mechanisms (7,35). Similarly, our previous experiments using isolated thoracic aorta demonstrated in Wistar and SHR that the pre-treatment with L-NAME, an inhibitor of NO-synthase, diminished the contractile vasoactive effects of low concentrations of H 2 S donor (14,15). ...
Perivascular adipose tissue (PVAT) and hydrogen sulfide (H2S) play important roles in the modulation of vasoactive responses and can interfere with the ethiopathogenesis of essential hypertension. The aim of this study was to evaluate the mutual relationship between PVAT and H2S (endogenously produced, exogenous) in vasoactive responses of isolated mesenteric arteries (MA) in adult normotensive (Wistar) and spontaneously hypertensive rats (SHR). In SHR, hypertension was associated with cardiac hypertrophy and increased contractility; however, there were no differences in the amount of
retroperitoneal fat between strains. PVAT revealed the anti-contractile effect on vasoconstriction induced by exogenous noradrenaline in both strains, but surprisingly, this effect was stronger in SHR. Concurrently; PVAT exhibited a procontractile effect on contractions to endogenous noradrenaline released from arterial sympathetic nerves in SHR, but not in Wistar rats. We confirmed the anti-contractile effect of H2S in both, the vascular wall and PVAT of Wistar rats because the pre-treatment with propargylglycine (PPG), an inhibitor of H2S producing enzyme, significantly increased the noradrenaline-induced contraction. In SHR, H2S in the vascular wall exhibited a pro-contractile effect that was eliminated by the presence of PVAT; however, the pre-treatment with PPG did not affect noradrenaline contraction farther. Nevertheless, unlike in Wistar rats, the presence of PVAT potentiated the vasorelaxant effect of exogenously applied H2S in SHR. Our results confirmed that PVAT of MA and endogenously produced H2S could manifest as pro-contractile or as anti-contractile. In SHR, unlike in Wistar rats, the pro-contractile effect of PVAT associated with the stimulation of perivascular nerves, and the pro-contractile effect of H2S in the arterial wall could represent pathologic features. On the
other hand, PVAT of SHR is endowed with compensatory vasoactive mechanisms, which include stronger anti-contractile action of an unknown factor (other than H2S) and potentiation of the vasorelaxant effect of exogenous H2S.
Ke y wo r d s : hydrogen sulfide, mesenteric artery, perivascular adipose tissue, Normotensive rats, spontaneously hypertensive rats, propargylglycine, nitric oxide, adipocyte-derived relaxing factor
... In a cell-free system, it has been shown that NO inhibits CBS activity by binding to the haem group of the enzyme [127]. In a similar manner, that is the formation of a five co-ordinate ferrous nitrosyl complex impairing the binding of CBS to cysteine of homocysteine [126], NaSH has also been shown to directly inhibit a recombinant form of bovine eNOS most likely by an interaction between co-factors such as NADPH or tetrahydrobiopterin [128,129]. On the other hand, it has also been shown that NO can increase H 2 S biosynthesis through increases in expression of CBS and CSE enzymes in vascular smooth cells [11,130]. While H 2 S has been shown to increase NO levels by increasing IL-1βinduced iNOS expression again in vascular smooth cells [131] through NF-κB activation by a mechanism involving the ERK1/2 signaling cascade. ...
... It facilitates the translocation of nuclear factor-like 2 (Nrf2) to the nucleus through modification of its binding partner, kelch- NO-H 2 S cross-talk in the vascular tissue. H 2 S decreases the expression level of NO-synthase (eNOS) in a cell-free system [128], while NO can either inhibit CBS activity in a cell free system [127] or increases the expression levels of CSE and CBS [11] to increase H 2 S synthesis. H 2 S activates eNOS by an Akt-dependent phosphorylation of the protein [132]. ...
Nitric oxide (NO) a gaseous free radical is one of the ten smallest molecules found in nature, while hydrogen sulfide (H2S) is a gas that bears the pungent smell of rotten eggs. Both are toxic yet they are gasotransmitters of physiological relevance. There appears to be an uncanny resemblance between the general actions of these two gasotransmitters in health and disease. The role of NO and H2S in cancer has been quite perplexing, as both tumor promotion and inflammatory activities as well as anti-tumor and antiinflammatory properties have been described. These paradoxes have been explained for both gasotransmitters in terms of each having a dual or biphasic effect that is dependent on the local flux of each gas. In this review/commentary, I have discussed the major roles of NO and H2S in carcinogenesis, evaluating their dual nature, focusing on the enzymes that contribute to this paradox and evaluate the pros and cons of inhibiting or inducing each of these enzymes.
... It also participates in regulating vascular tension and blood fow distribution, thereby afecting the occurrence and development of cardiovascular and cerebrovascular diseases [22]. NO alone or in synergy with H 2 S can relax vascular smooth muscle; moreover, a single application of H 2 S only arouses a very weak vasodilation efect, which can be amplifed in the presence of NO [23]. ...
Background:
Endothelial cell senescence is one of the key mechanistic factors in the pathogenesis of atherosclerosis. In terms of molecules, the phosphatidylinositol 3-kinase/protein kinase B/endothelial nitric oxide synthase (PI3K/Akt/eNOS) signaling plays an important role in the prevention and control of endothelial cell senescence, while hydrogen sulfide (H2S) improves the induced precocious senescence of endothelial cells through the PI3K/Akt/eNOS pathway. Comparatively, replicative senescence in endothelial cells is more in line with the actual physiological changes of human aging. This study aims to investigate the mechanism by which H2S improves endothelial cell replicative senescence and the involvement of the PI3K/Akt/eNOS pathway.
Methods:
we established a model of replicative senescence in human umbilical vein endothelial cells (HUVECs) and explored the effect of 200 μmol/L sodium hydrosulfide (NaHS; a donor of H2S) on senescence, which was determined by cell morphology, the expression level of plasminogen activator inhibitor 1 (PAI-1), and the positive rate of senescence-associated β-galactosidase (SA-β-Gal) staining. Cell viability was detected by MTT assay to evaluate the effect of NaHS and the PI3K inhibitor, LY294002. Meanwhile, the protein expression of PI3K, Akt, p-Akt, and eNOS in endothelial cells of each group was detected by Western blot.
Results:
the replicative senescence model was established in HUVECs at the passage of 16 cumulative cell population doubling values (CPDL). Treatment with NaHS not only significantly reduced the expression of PAI-1 and the positive rate of SA-β-Gal in HUVEC's replicative senescence model but also notably increased the expression of PI3K, p-Akt, p-eNOS, and the content of nitric oxide(NO). However, the effects of NaHS on the expression of the pathway and the content of NO in HUVECs were abolished when LY294002 specifically inhibited PI3K.
Conclusion:
NaHS improves the replicative senescence of HUVECs with the contribution of the PI3K/Akt/eNOS pathway.
... Inhibition of NO synthase or increased superoxide production may be responsible for the unavailability of NOdependent vascular relaxation [49]. When the tissue was pretreated with L -NAME, an inhibitor of nitric oxide synthase [50,51], it reduced the vasorelaxant effect caused by Ma.Cr and fractions similar to denuded tissues. This is an evidence of the involvement of endothelium-based relaxation and NO release. ...
Melia azedarach L. leaves have been traditionally used but not scientifically evaluated for antihypertensive activity. The focus of the present work was to carry out the detailed phytochemical profiling and antihypertensive potential of methanolic extract and subsequent fractions of this plant. The tandem mass spectrometry-based phytochemical profiling of M. azedarach extract (Ma.Cr) and fractions was determined in negative ionization mode while molecular networking was executed using the Global Natural Product Social (GNPS) molecular networking platform. This study resulted in the identification of 29 compounds including flavonoid O-glycosides, simple flavonoids, triterpenoidal saponins, and cardenolides as the major constituents. Ma.Cr at the concentration of 300 mg/kg resulted in a fall in blood pressure (BP), i.e., 81.44 ± 2.1 mmHg in high salt-induced hypertensive rats in vivo, in comparison to normotensive group, i.e., 65.36 ± 1.8 mmHg at the same dose. A decrease in blood pressure was observed in anaesthetized normotensive and hypertensive rats treated with extract and various fractions of M. azedarach. A reasonable activity was observed for all fractions except the aqueous fraction. The highest efficacy was shown by the ethyl acetate fraction, i.e., 77.06 ± 3.77 mmHg in normotensive and 88.96 ± 1.3 mmHg in hypertensive anaesthetized rats. Ma.Cr and fractions showed comparatively better efficacy towards hypertensive rats as compared to rats with normal blood pressure. Blood pressure-lowering effects did not change upon prior incubation with atropine. In vitro testing of Ma.Cr and polarity-based fractions resulted in L-NAME sensitive, endothelium-dependent vasodilator effects on aortic tissues. Pretreatment of aorta preparations with Ma.Cr and its fractions also blocked K+-induced precontractions indicating Ca2+ channel blocking activity comparable to verapamil. The extract and polarity-based fractions did not reveal a vasoconstrictor response in spontaneously beating isolated rat aorta. Ma.Cr and fractions when used in atrial preparations resulted in negative inotropic and chronotropic effects. These effects in atrial preparations did not change in the presence of atropine. These effects of extract and fractions explained the antihypertensive potential of M. azedarach and thus provided a scientific basis for its ethnopharmacological use in the treatment of hypertension. Among the constituents observed, flavonoids and flavonoid O-glycosides were previously reported for antihypertensive potential.
... [26,77] Also, NO can bind with the haem group of CBS, inhibiting H 2 S biosynthesis, while H 2 S may inhibit NO production by inactivating the isoform nitric oxide synthases. [78][79][80] These evidences encourage researchers to use H 2 S and NO, either alone or combined, as therapeutic agents in wound healing. However, exogeneous delivery of these gases in a sustained and targeted manner is challenging and a variety of delivery systems have been proposed but only few are Food and Drug Administration (FDA) approved products. ...
Nitric oxide (NO) and hydrogen sulfide (H2S) have been recognized as important signalling molecules involved in multiple physiological functions, including wound healing. Their exogenous delivery has been established as a new route for therapies, being the topical application the nearest to commercialization. Nevertheless, the gaseous nature of these therapeutic agents and their toxicity at high levels imply additional challenges in the design of effective delivery systems, including the tailoring of their morphology and surface chemistry to get controllable release kinetics and suitable lifetimes. This review highlights the increasing interest in the use of these gases in wound healing applications by presenting the various potential strategies in which NO and/or H2S are the main therapeutic agents, with focus on their conceptual design, release behaviour and therapeutic performance. These strategies comprise the application of several types of nanoparticles, polymers, porous materials, and composites as new releasing carriers of NO and H2S, with characteristics that will facilitate the application of these molecules in the clinical practice.
... У серцевосудинній системі сірководень пригнічує проліферацію ГМК, модулюючи МАР-кіназний сигнальний шлях [31]. Cірководень може викликати і скорочення сегментів аорти щура через зміну внутрішньоклітинної концентрації циклічного аденозинмонофосфату (цАМФ) або активацію Cl/НСО 3 обмінника й ацидифікацію цитоплазми ГМК [29]. ...
Medical hydrology and rehabilitation 2013.-11, №1. – P. 117-122.
The role of endogenous hydrogen sulfide in the regulation of vascular tone, cell proliferation and apoptosis was analysed. The data pertains to endogenous formation and the mechanisms of hydrogen sulfide action. Information about the cardio-, nephro-and cytoprotection of gazotransmitter was summarized. In experimental systems, H2S or H2S donors (most commonly NaHS) provide protection in many physiological systems, including the cardiovascular system, brain, lungs, and gastrointestinal system. Most notably, they attenuate vasoconstriction and reduce damage (e.g., myocardial infarct size) in several animal models of cardiovascular disease (e.g., myocardial ischemia-reperfusion, cardiopulmonary bypass). Conversely, inhibitors of H2S synthesis raise blood pressure in rats. The effects of H2S on cells, studied using H2S donors, are variable. In part, effects are dose dependent. Lower (micromolar) levels are generally cytoprotective, with protection often ascribed to a reduction or neutralization of reactive oxygen and nitrogen species. At millimolar levels, H2S is often cytotoxic or pro-apoptotic.
... [22], ! [25, 31,32]. ...
We analysed the modern literature about the hydrogen sulfide role in evolution of atmosphere, phylogenesis and possibility the use of its vazodylyatation properties for treatment and rehabilitation in sanatorium-resort terms. The mechanisms of gumoral and reflex action of hydrogen sulfide and sulfides baths are considered, testimonies, relative and absolute contra-indications, are resulted. It was shown that at the correct dosage and account of the initial state of reactivity of patient hydrogen sulfide can be the substantial factor for the local blood stream improvement, the trophic and regeneration processes activating, the whole organism physiological state renewal.
... Although most studies have shown that H 2 S positively cooperates with NO in the vascular system, the concentrations of H 2 S donors used are relatively high in these studies. In contrast, less than 100 µM NaHS is shown to be paradoxically vasoconstrictive by suppressing cAMP production in vascular SMC, and to reverse vasorelaxation induced by endothelium-derived vasodilators such as acetylcholine and histamine; this contractile activity of H 2 S is attributed to the direct inhibition of eNOS [380]. In addition, high concentrations of H 2 S, like NO and CO, are cytotoxic and induce cell death. ...
Normal pregnancy is associated with dramatic increases in uterine blood flow to facilitate the bidirectional maternal–fetal exchanges of respiratory gases and to provide sole nutrient support for fetal growth and survival. The mechanism(s) underlying pregnancy-associated uterine vasodilation remain incompletely understood, but this is associated with elevated estrogens, which stimulate specific estrogen receptor (ER)-dependent vasodilator production in the uterine artery (UA). The classical ERs (ER and ER) and the plasma membrane-bound G protein-coupled ER (GPR30/GPER) are expressed in UA endothelial cells and smooth muscle cells, mediating the vasodilatory effects of estrogens through genomic and/or nongenomic pathways that are likely epigenetically modified. This chapter aims to summarize the literature on UA ERs with a focus on their roles in mediating the local UA production of vasodilators by estrogens and pregnancy and to deliberate on the potential clinic implications of dysregulated ER-mediated estrogen signaling in hypertensive pregnancy complications. The activation of these three ERs by estrogens enhances the endothelial production of nitric oxide (NO), which has been shown to play a key role in uterine vasodilation during pregnancy. However, the local blockade of NO biosynthesis only partially attenuates estrogen-induced and pregnancy-associated uterine vasodilation, suggesting that mechanisms other than NO exist to mediate uterine vasodilation. We summarize here the literature on the role of NO in ER-mediated mechanisms controlling estrogen-induced and pregnancy-associated uterine vasodilation and our recent work on a “new” UA vasodilator hydrogen sulfide (H2S) that has dramatically changed our view of how estrogens regulate uterine vasodilation in pregnancy.
... Okrem mechanizmov nezávislých od NO, vazokonstriktorický účinok H 2 S môže závisieť od prítomnosti endogénne syntetizovaného NO (22). Zistilo sa, že nízke koncentrácie H 2 S vyvolávajú down-reguláciu L-arginín/NO dráhy v kultivovaných aj izolovaných cievnych tkanivách prostredníctvom niekoľkých mechanizmov (22,23). Obdobne naše predchádzajúce experimenty s použitím izolovanej hrudnej aorty preukázali u Wistar a SHR, že inkubácia ciev s L-NAME, inhibítorom NO-syntázy, zmenšila kontraktilné účinky nízkych koncentrácií donora H 2 S (9, 10). ...
... The opening of potassium channels leads to hyperpolarization and smooth muscle relaxation. Different types of K channels are involved in H 2 S vasodilatation, including in large arteries ATP-sensitive K channels (K ATP ) (Zhao and Wang, 2002;Kubo et al., 2007;Webb et al., 2008;Martelli et al., 2013a), voltage-gated K channels (K V 7, KCNQ) (Martelli et al., 2013a;Hedegaard et al., 2014), and 4aminopyridine-sensitive voltage-gated potassium channels (Cheang et al., 2010). In resistance arteries, H 2 S vasodilatation involves K ATP channels (Tang et al., 2005), large-conductance calcium-dependent potassium channels (BK Ca ) (Jackson-Weaver et al., 2011;Jackson-Weaver et al., 2013), and K V 7 channels (Schleifenbaum et al., 2010;Hedegaard et al., 2016), but also potassium channel-independent vasodilatation (Hedegaard et al., 2016). ...
Donors of H2S may be beneficial in treating cardiovascular diseases where the plasma levels of H2S are decreased. Therefore, we investigated the mechanisms involved in relaxation of small arteries induced by GYY4137 [(4-methoxyphenyl)-morpholin-4-yl-sulfanylidene-sulfido-λ5-phosphane;morpholin-4-ium], which is considered a slow-releasing H2S donor. Sulfides were measured by use of 5,5′-dithiobis-(2-nitro benzoic acid), and small rat mesenteric arteries with internal diameters of 200–250 µm were mounted in microvascular myographs for isometric tension recordings. GYY4137 produced similar low levels of sulfides in the absence and the presence of arteries. In U46619-contracted small mesenteric arteries, GYY4137 (10⁻⁶–10–3 M) induced concentration-dependent relaxations, while a synthetic, sulfur-free, GYY4137 did not change the vascular tone. L-cysteine (10⁻⁶–10–3 M) induced only small relaxations reaching 24 ± 6% at 10–3 M. Premixing L-cysteine (10–3 M) with Na2S and GYY4137 decreased Na2S relaxation and abolished GYY4137 relaxation, an effect prevented by an nitric oxide (NO) synthase inhibitor, L-NAME (Nω-nitro-L-arginine methyl ester). In arteries without endothelium or in the presence of L-NAME, relaxation curves for GYY4137 were rightward shifted. High extracellular K⁺ concentrations decreased Na2S and abolished GYY4137 relaxation suggesting potassium channel-independent mechanisms are also involved Na2S relaxation while potassium channel activation is pivotal for GYY4137 relaxation in small arteries. Blockers of large-conductance calcium-activated (BKCa) and voltage-gated type 7 (KV7) potassium channels also inhibited GYY4137 relaxations. The present findings suggest that L-cysteine by reaction with Na2S and GYY4137 and formation of sulfides, inhibits relaxations by these compounds. The low rate of release of H2S species from GYY4137 is reflected by the different sensitivity of these relaxations towards high K⁺ concentration and potassium channel blockers compared with Na2S. The perspective is that the rate of release of sulfides plays an important for the effects of H2S salt vs. donors in small arteries, and hence for a beneficial effect of GYY4137 for treatment of cardiovascular disease.
... However, studies reporting conflicting results are available in the current literature. For instance, H 2 S inhibited the activity of eNOS in rat and mouse aortic rings (41), and both exogenous and endogenous H 2 S reduced NO generation and prevented eNOS activity and transcription (42). Additionally, in the present study, a slight non-significant increase of iNOS expression was observed with L-NAME administration, while the administration of NaHS and PAG in combination with L-NAME resulted in decreased expression. ...
Background/aim:
This study was designed to provide further evidence for the interactions between hydrogen sulfide (H2S) and nitric oxide (NO) in ischemia/reperfusion (I/R) injury.
Materials and methods:
Rat hearts were studied with the Langendorff technique using the H2S donor sodium hydrosulfide (NaHS, 40 μM) and the cystathionine gamma-lyase (CTH or CSE) inhibitor DL-propargylglycine (PAG, 1 mM). NO synthase inhibitor L-NG-nitroarginine methyl ester (L-NAME, 30 mg/kg, 7 days) was administered before the isolation. The hearts were homogenized for biochemical and molecular analysis.
Results:
NaHS reversed I/R-induced cardiac performance impairment, increased tissue nitric oxide production and decreased tissue markers for cardiac injury, while L-NAME inhibited these effects. The expression of CTH was increased with PAG, which was suppressed by L-NAME.
Conclusion:
H2S and NO increase each other's production suggesting their interaction and cooperation in cardioprotection against I/R injury.
... Studies have suggested the anti-inflammatory and antioxidant activity of H2S [50]. According to Kubo et al., NaHS (a H2S donor) is capable of inhibiting endothelial nitric oxide synthase (eNOS) activity and may have systolic effect on blood vessels in the absence of NO [51]. Moreover, changes in H2S levels have been linked to the development and progression of kidney diseases, from the acute to the chronic stage [41,42,[52][53][54][55]. ...
Acute kidney injury (AKI) is a syndrome affecting most patients hospitalized due to kidney disease; it accounts for 15 % of patients hospitalized in intensive care units worldwide. AKI is mainly caused by ischemia and reperfusion (IR) injury, which temporarily obstructs the blood flow, increases inflammation processes and induces oxidative stress. AKI treatments available nowadays present notable disadvantages, mostly for patients with other comorbidities. Thus, it is important to investigate different approaches to help minimizing side effects such as the ones observed in patients subjected to the aforementioned treatments. Therefore, the aim of the current review is to highlight the potential of two endogenous gasotransmitters - hydrogen sulfide (H2S) and nitric oxide (NO) - and their crosstalk in AKI treatment. Both H2S and NO are endogenous signalling molecules involved in several physiological and pathophysiological processes, such as the ones taking place in the renal system. Overall, these molecules act by decreasing inflammation, controlling reactive oxygen species (ROS) concentrations, activating/inactivating pro-inflammatory cytokines, as well as promoting vasodilation and decreasing apoptosis, hypertrophy and autophagy. Since these gasotransmitters are found in gaseous state at environmental conditions, they can be directly applied by inhalation, or in combination with H2S and NO donors, which are compounds capable of releasing these molecules at biological conditions, thus enabling higher stability and slow release of NO and H2S. Moreover, the combination between these donor compounds and nanomaterials has the potential to enable targeted treatments, reduce side effects and increase the potential of H2S and NO. Finally, it is essential highlighting challenges to, and perspectives in, pharmacological applications of H2S and NO to treat AKI, mainly in combination with nanoparticulated delivery platforms.
... Н 2 S эффективно расслабляет гладкие мышцы кишечника, интактные и деэндотелизированные сосудистые сегменты, активируя аденозинтрифосфатчувствительные калиевые каналы ГМК или Са 2+зависимые калиевые каналы большой проводимости и потенциалзависимые аминопиридин-чувствительные калиевые каналы [2,9,10]. По данным S. Kubo, сероводород может вызывать и сокращение сегментов аорты крысы через изменение внутриклеточной концентрации циклического аденозинмонофосфата (цАМФ) или активацию Cl/НСО 3 обменника и ацидификацию цитоплазмы ГМК [3]. ...
In preparations of rat aorta, used as a model of muscular type arteries, the method mehanografii studied the effect of hydrogen sulfide on the reduction of isolated of vascular smooth muscle. Found that hydrogen sulfide in concentrations 1—50 mmol increases the mechanical stress of smooth muscle in high-K + medium. At higher concentrations (300—1 000 mmol) H2S leads to lower amplitude giperkalievoy contraction in high-K + medium. Reduction of smooth muscle cells caused by phenylephrine inhibited the action of hydrogen sulfide in the whole range of concentrations. The causes of differences in data obtained with the results of studies in other laboratories, and possible mechanisms of action of hydrogen sulfide on the contractile activity of vascular smooth muscle.
... As critical co-effectors of angiogenesis, gas cross-talk between nitric oxide (NO) and hydrogen sulfide (H 2 S) was a good example. NO and H 2 S not only had mutual interaction by changing the expression and activity of enzymes [30], but also mutually regulated the same downstream signaling pathways. Sirt1 was found to be a common downstream signal target of NO and H 2 S. ...
... NO and H 2 S can interact with each other, affecting each other's bioavailability and reactivity [34][35][36]. For example, NO inhibits CBS activity by binding to the heme group of the enzyme [37] and NaSH inhibits a recombinant form of bovine eNOS by an interaction between co-factors such as NADPH or tetrahydrobiopterin [38,39]. NO can increase H 2 S biosynthesis through increases in expression of CBS and CSE enzymes in vascular smooth cells [26,40]. ...
Nitric oxide (NO) and hydrogen sulfide (H2S) are industrial toxins or pollutants; however, both are produced endogenously and have important biological roles in most mammalian tissues. The recognition that these gasotransmitters have a role in physiological and pathophysiological processes has presented opportunities to harness their intracellular effects either through inhibition of their production; or more commonly, through inducing their levels and or delivering them by various modalities. In this review article, we have focused on an array of NO and H2S donors, their hybrids with other established class of drugs, and the various engineered delivery platforms such a fibers, polymers, nanoparticles, hydrogels, and others. In each case, we have reviewed the rationale for their development.
... Studies on the crosstalk between NO and H 2 S at the vascular level have demonstrated that H 2 S interacts with the eNOS/NO pathway and that NO interacts with the CSE/H 2 S pathway (Nagpure & Bian, 2016;Whiteman & Moore, 2009); H 2 S is thought to increase the NO/sGC/cGMP pathway by increasing the vasorelaxant effect of NO and the NO-responsive form of GC, inhibiting PDEs (Bucci et al., 2010;Hosoki, Matsuki, & Kimura, 1997;Kanagy et al., 2017;Wang et al., 2015). In parallel, NO increases the activity and the expression of CSE, enhancing H 2 S production (Kubo, Doe, Kurokawa, Nishikawa, & Kawabata, 2007;Szabo, 2016;Zhao, Zhang, Lu, & Wang, 2001). However, the majority of the data present in the current relevant literature have been obtained by using exogenous sources of H 2 S and/or NO (i.e., H 2 S and NO donors). ...
Background and Purpose
Among the three enzymes involved in the transsulfuration pathway, only cystathionine β‐synthase (CBS) converts L‐cysteine into L‐serine and H2S. L‐serine is also involved in the de novo sphingolipid biosynthesis through a condensation with palmitoyl‐CoA by the action of serine palmitoyltransferase (SPT). Here, we have investigated if L‐serine contributes to the vasorelaxant effect.
Experimental Approach
The presence of CBS in mouse vascular endothelium was assessed by immunohistochemistry and immunofluorescence. The relaxant activity of L‐serine (0.1–300 μM) and L‐cysteine (0.1–300 μM) was estimated on mouse aorta rings, with or without endothelium. A pharmacological modulation study evaluated NO and sphingosine‐1‐phosphate (S1P) involvement. Levels of NO and S1P were also measured following incubation of aorta tissue with either L‐serine (1, 10, and 100 μM) or L‐cysteine (10, 100 μM, and 1 mM).
Key Results
L‐serine relaxed aorta rings in an endothelium‐dependent manner. The vascular effect was reduced by L‐NG‐nitro‐arginine methyl ester and wortmaninn. A similar pattern was obtained with L‐cysteine. The S1P1 receptor antagonist (W146) or the SPT inhibitor (myriocin) reduced either L‐serine or L‐cysteine relaxant effect. L‐serine or L‐cysteine incubation increased NO and S1P levels in mouse aorta.
Conclusions and Implications
L‐serine, a by‐product formed within the transsulfuration pathway starting from L‐cysteine via CBS, contributes to the vasodilator action of L‐cysteine. The L‐serine effect involves both NO and S1P. This mechanism could be involved in the marked dysregulation of vascular tone in hyperhomocysteinemic patients (CBS deficiency) and may represent a feasible therapeutic target.
Linked Articles
This article is part of a themed section on Hydrogen Sulfide in Biology & Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.4/issuetoc
... previous in vitro experiments (8) and the present data also suggested that NOindependent pathways are responsible for the vasorelaxant effects of h 2 S. the pretreatment with L-NAME diminished the contractile part but did not inhibit the relaxant part of the vasoactive Na 2 S effects in young and adult normotensive rats as well as it did in ShR (Fig. 4b). We supposed that the vasoconstrictor effects of h 2 S were probably related to its inhibitory effect on the endogenous NO/NOS system since acute L-NAME treatment disabled the inhibitory effect of Na 2 S on NO production, thus masking the contractile effect of h 2 S. Other authors also confirmed that NahS, another h 2 S donor, directly inhibited the activity of recombinant endothelial NOS, possibly via the interaction of h 2 S with co-factors for NOS, such as NADph or tetrahydrobiopterin (37). Moreover, geng et al. (12) confirmed that NahS inhibited NO generation in cultured aortic tissue and that low doses of NahS could downregulate the Larginine/NO pathway through the inhibition of endothelial NOS expression and L-arginine transporters and/or a decrease in NOS activity. ...
Several studies have already confirmed the specific vasomotor effect of hydrogen sulfide (H2S) and its interaction with the nitric oxide (NO) system in normotensive rats, but results in spontaneously hypertensive rats (SHRs) are limited. the aim of this study was to describe the age- and blood pressure-dependent effects of endogenous NO and exogenous Na2S and their interaction in vasomotor responses of the thoracic aorta (TA) in normotensive Wistar rats and SHRs. the systolic blood pressure (sBP), vasoactivity, NO-synthase (NOS) expression and activity, cystathionine gamma-lyase (CSE) expression, and geometry of the isolated TA were evaluated at 4 and 16 weeks of age. Although hypertrophy of the heart was observed in young and adult SHRs, the sBP was increased only in adulthood. the contractile responses were decreased in young as in adult SHRs with the key participation of the endogenous NO system. however, the hypotrophy in the young and the hypertrophy (mainly at the expense of extracellular matrix) in the adult SHRs were found in the TA. While unchanged in young SHRs, in adult SHRs, partially impaired endothelial function was confirmed. Nevertheless, the NO-dependent component of acetylcholine-induced relaxation was higher in both young and adult SHRs. Consistently, even though there was an age-dependent decrease in NOS activity in both strains, NOS activity was higher in both young and adult SHRs compared to age-matched normotensive rats. Application of exogenous Na2S evoked a concentration-dependent dual vasoactive effect of TAs in both strains, regardless of age. Increased sensitivity in favor of vasorelaxant responses of Na2S in prehypertensive SHRs, and an enhanced maximal vasorelaxation in adult SHR was observed. the acute NO inhibition generally increased the relaxant phase of Na2S responses; nevertheless, the development of hypertension potentiated this effect. the TA of the SHRs is endowed with a unique inherent predisposition of vasoactive mechanisms, which serve as compensatory processes during the developed stage of hypertension: the NO component and H2S signaling pathways are implicated. the decreased contractility seems to be a deleterious effect. the increased participation of the H2S system on vasorelaxation after acute NO inhibition could be considered a reserved mechanism in case of endogenous NO deficiency.
... L-sistein ve ekzojen H2S'in inhibe edici etkisinin olduğu, tavşan mide şeritleri ve insan alt özofagus sifinkteri muskarinik kasılma yanıtları, tavşan alt özofagus sifinkterinde ise nörojenik kasılmalar ve insan kolonundaki spontan kasılmar üzerinde gösterilmiştir [24][25][26][27] . Bulgumuzun ters yönünde, sıçan ve fare aorta dokusunda ise, ekzojen H2S varlığında fenilefrin ve KCl kasılmalarında artış gözlenmiştir 28 . Doku farklılığından kaynaklanabileceğini düşündürmektedir. ...
Amaç:Çalışmamızda, fare mide fundus
dokusunda L-sistein/ hidrojen sülfür (H2S) yolağının potasyum klorür
(KCl) kasılma yanıtları üzerindeki etkisi ve bu etkide nitrik oksid (NO) ve
siklooksijenaz (COX) yolaklarının olası katkılarının araştırılması
amaçlanmıştır.Gereç ve Yöntem:İzole fare fundus şeritlerinde,
kümülatif KCl (10-80 mM) ile kasılma yanıtları oluşturulup, L-sistein (10 mM)’in
bu kasılma yanıtları üzerindeki etkisi incelendi. Ayrıca, H2S’in
endojen olarak sentezine aracılık eden sistatyon beta-sentaz (CBS) enzim inhibitörü
aminooksiasetik asid (AOAA; 1 mM) ve sistatyon gamma-liyaz (CSE) enzim
inhibitörü proparjil glisin (PAG, 10 mM) varlığında, L-sistein ’in KCl kasılma
yanıtları üzerindeki etkisi araştırıldı.
L-sistein’in KCl kasılmaları üzerindeki etkisine NO ve COX yolaklarının
olası katkısı, nitrik oksid sentaz (NOS)
enzim inhibitörü L-Nitroarjinin (L-NA; 0.1 mM) ve non-selektif COX enzim
inhibitörü indometazin (0.001 mM) varlığında incelendi. Bulgular: L-sistein, KCl kasılma
yanıtlarında inhibe edici bir etki oluşturdu. AOAA, L-sistein ’in KCl
kasılmaları üzerindeki inhibe edici etkisinin geri çevrilmesine neden oldu. PAG
varlığında ise, L-sistein ’in düşük konsantrasyonlardaki KCl kasılma yanıtları
üzerindeki inhibe edici etkisinin azaldığı gözlendi. L-NA içeren ortamda, L-sistein sadece maksimum KCl kasılma
yanıtında bir inhibisyona neden oldu. Bu inhibe edici etki, AOAA ve PAG ile geri çevrildi. İndometazin
ise, L-sistein ’in KCl kasılmaları üzerindeki düşük konsantrasyondaki inhibe
edici etkisinin azalmasına neden oldu. Ayrıca, ortamda L-NA ile indometazin
kombinasyonunu varlığında, L-sistein ’in kasılma yanıtları üzerinde neden
olduğu inhibisyon PAG ve AOAA ile geri çevrildi. Sonuç:Bu bulgular, fare fundus dokusunda L-sistein/ H2S yolağının KCl kasılma yanıtları
üzerinde inhibitör etkisinin olduğunu ve bu etkinin NO ve COX yolakları ile
ilişkili olabileceğini düşündürmektedir.
... Currently, the information on nNOS modulation by H 2 S is scarce. Besides its inhibition at high nonphysiological sulfide concentrations (IC 50 = 130 μM) [233,236], nNOS expression seems to be either insensitive to sulfide exposure or decreased upon overexpression of the H 2 S-synthesizing CBS in hypertensive (but not normotensive) rats [237]. ...
Hydrogen sulfide (H 2 S) has emerged as a relevant signaling molecule in physiology, taking its seat as a bona fide gasotransmitter akin to nitric oxide (NO) and carbon monoxide (CO). After being merely regarded as a toxic poisonous molecule, it is now recognized that mammalian cells are equipped with sophisticated enzymatic systems for H 2 S production and breakdown. The signaling role of H 2 S is mainly related to its ability to modify different protein targets, particularly by promoting persulfidation of protein cysteine residues and by interacting with metal centers, mostly hemes. H 2 S has been shown to regulate a myriad of cellular processes with multiple physiological consequences. As such, dysfunctional H 2 S metabolism is increasingly implicated in different pathologies, from cardiovascular and neurodegenerative diseases to cancer. As a highly diffusible reactive species, the intra- and extracellular levels of H 2 S have to be kept under tight control and, accordingly, regulation of H 2 S metabolism occurs at different levels. Interestingly, even though H 2 S, NO, and CO have similar modes of action and parallel regulatory targets or precisely because of that, there is increasing evidence of a crosstalk between the three gasotransmitters. Herein are reviewed the biochemistry, metabolism, and signaling function of hydrogen sulfide, as well as its interplay with the other gasotransmitters, NO and CO.
... H 2 S also increased eNOS activity through promoting its phosphorylation (Altaany et al. 2014). On the contrary, high concentration of NaHS (300-3000 μM) significantly inhibited the activity of recombinant bovine eNOS (Kubo et al. 2007). Furthermore, the mechanisms by which H 2 S regulates eNOS remain to be clarified. ...
Hydrogen sulfide (H2S) is a gaseous mediator recognized as important neuromodulator agent in the central nervous system. Since stress is among the most important factors involved in several pathophysiological brain processes. This study aim to investigate the effect of exogenous H2S on the possible negative effect of stress on the brain of rats and the underlying mechanisms. Rats were divided into 3 groups: control, stressed, H2S treated + stress. Brain injury markers measured were serum S100 protein and gamma enolase. Stress leads to obvious detrimental effects on the brain tissues; it produced significant increase in serum level of the above mentioned brain injury markers, and significant increase in brain levels of nitric oxide (NO), tumor necrosis factor-alpha (TNFα), and malondialdehyde (MDA) the lipid peroxidation degradative product along with significant decrease in brain glutathione level. H2S pre-treatment before stress application abolished the above detrimental effects of stress on the brain tissue since it produced significant decreases in the stressinduced expression of brain injury markers, brain TNFα, brain NO and brain MDA, and significant increases in the stress-induced reduction of brain glutathione. H2S has significant neuroprotective role in the nervous system against stress-induced significant brain injury through its antioxidant and anti-inflammatory effects.
... However, some conflicting effects have also been reported. Data from experiments on rat and mouse aortic rings showed that H 2 S directly inhibited recombinant bovine eNOS activity [28]. In another study, exogenous and endogenous H 2 S inhibited eNOS transcription and activity [29]. ...
Nitric oxide (NO) and hydrogen sulfide (H2S) are now recognized as gaseous transmitters with many cardiovascular protective properties. The present study concerns the possibility that NO donors can also function through endogenous activation of NO and H2S pathways. Based on the previous characterization of a novel metal-nonoate, Ni(PipNONO)Cl, our aim was: 1) to study the effects of a zinc based compound, Zn(PipNONO)Cl, on vascular endothelial and smooth muscle cells, and 2) to assess the role and interplay between endogenous NO and H2S promoted by the nonoate. Zn(PipNONO)Cl completely reproduced the vasodilation elicited by Ni(PipNONO)Cl. In the presence of endothelium, preincubation with Zn(PipNONO)Cl sensitized the intima to acetylcholine-induced vasodilation. When tested on cultured endothelial cells, Zn(PipNONO)Cl promptedPI-3K/Akt- and MAPK/ERK1/2-mediated survival. Nitrite levels indicated fast NO release (due to the molecule) and delayed (1-6 h) NO production linked to PI-3K/Akt-dependent eNOS activation. In the same time frame (1-6 h), significant CSE-dependent H2S levels were detected in response to Zn(PipNONO)Cl. The mechanisms responsible for H2S increase seemed to depend on the NONO moiety/sGC/cGMP pathway and zinc-associated ROS production. Our results indicate that endogenous H2S and NO were produced after fast NO release from Zn(PipNONO)Cl, contributing to the vascular endothelium protective effect. The effect was partially reproduced on smooth muscle cells, where Zn(PipNONO)Cl inhibited cell proliferation and migration. In conclusion, vasorelaxant effects, with complementary activities on endothelium and smooth muscle cells, are elicited by the novel metal-nonoate Zn(PipNONO)Cl.
... In this paper, the tail temperature was used as a measure of central activation of peripheral cooling mechanisms (i.e., peripheral vasodilation), as has been used before in the determination of thermoregulatory peripheral vasoactivity in pyrexic mice 38 . However, as reviewed by Liu et al., H 2 S has biphasic effects on the vascular tone: at low concentrations H 2 S induces vasoconstriction and at higher doses vasodilation is induced, as evidenced in mouse and rat aortic tissue [62][63][64] . Consequently, the absence of thermoregulatory vasodilation and a consequent increase in the tail temperature of 3 animals (Fig. 4) could also be a direct vasoconstrictive effect of low-dose H 2 S. Nevertheless, H 2 S-induced vasoconstriction is unlikely to be responsible for the absence of H 2 S-induced hypothermia in our experiments. ...
Hydrogen sulfide (H2S, 80 ppm) gas in an atmosphere of 17.5% oxygen reportedly induces suspended animation in mice; a state analogous to hibernation that entails hypothermia and hypometabolism. However, exogenous H2S in combination with 17.5% oxygen is able to induce hypoxia, which in itself is a trigger of hypometabolism/hypothermia. Using non-invasive thermographic imaging, we demonstrated that mice exposed to hypoxia (5% oxygen) reduce their body temperature to ambient temperature. In contrast, animals exposed to 80 ppm H2S under normoxic conditions did not exhibit a reduction in body temperature compared to normoxic controls. In conclusion, mice induce hypothermia in response to hypoxia but not H2S gas, which contradicts the reported findings and putative contentions.
... In addition, patch-clamp studies have demonstrated that H 2 S increases K ATP -dependent current and induces hyperpolarization in mammalian vascular smooth muscle cells (62,63). However, glibenclamide failed to affect the relaxing effect of H 2 S in mouse aorta (64) and rat coronary artery (65). In the latter vessel, H 2 S-induced relaxation was impaired by the presence of the K V channel blocker 4-AP (65). ...
Hydrogen sulfide (H2S) has recently emerged as a biologically active gas with multiple effects on the cardiovascular system. We aimed to investigate the vasomotor actions of sodium sulfide (Na2S), which forms H2S and HS- in solution, in human umbilical artery (HUA) and vein (HUV) rings. In addition, we examined by immunocytochemistry the expression and localization of cystathionine β-synthase (CBS), cystathionine lyase (CSE), and 3-mercaptopyruvate sulphurtransferase (MPST), the enzymes responsible for endogenous H2S production. Human umbilical vessels were compared with chicken embryo umbilical vessels. HUA and HUV expressed a robust signal for CSE, CBS, and 3-MPST in both endothelial and smooth muscle cells. However, HUA rings did not respond to Na2S (10-6M-10-3M) either at resting tone or during contraction evoked by serotonin or KCl. Similarly, the extraembryonic part of chicken allantoic artery did not respond to Na2S. In contrast, Na2S induced a concentration-dependent contraction in HUV rings under resting tone and a concentration-dependent relaxation when the H2UV rings were contracted with serotonin (42 ± 5% relaxation) or KCl (12 ± 5% relaxation). Na2S-induced contraction of HUV was impaired following removal of extracellular Ca2+, endothelial denudation, NO synthase inhibition (L-NAME), or soluble guanylate cyclase (sGC) inhibition (ODQ). Na2S-induced relaxation of HUV was impaired by the KATP channel inhibitor glibenclamide. In conclusion, H2S does not have vasomotor effects on HUA but induced contraction (mediated through inactivation of the NO/sGC axis) and relaxation (mediated through KATP channels) in HUV. Our data suggest a role for H2S in the venous side of human umbilical circulation.
... On the other hand, some observations revealed an opposite effect of H 2 S on smooth muscle cells of the arterial wall. Lower concentrations of H 2 S (Na 2 S: 3 μmol/kg; 10-100 μmol/L) resulted in blood pressure increase and vasoconstriction of the same vessels [105,[196][197][198]. Published data indicate numerous possible mechanisms of H 2 S-induced vasoconstriction. ...
In addition to nitric oxide and carbon monoxide, hydrogen sulfde (H2S) is the third gasotransmitter in mammals.
It is synthesized from L-cysteine by cystathionine β-synthase, cystathionine γ-lyase or by sequential action of alanine
aminotransferase and 3-mercaptopyruvate sulfur transferase. Although initially it was suggested that in the vascular
wall H
2S is synthesized only by smooth muscle cells and relaxes them by activating ATP-sensitive potassium channels,
more recent studies indicate that H
2S is synthesized in endothelial cells as well. The physiological functions of H2S
are mediated by different molecular targets, such as different ion channels and signaling proteins. Endogenous H2S is involved in the regulation of many physiological processes in the cardiovascular system including the regulation of vascular tone, blood pressure and inhibits atherogenesis. Many new technologies have been developed to detect endogenous H2S production, and novel H2S-delivery compounds have been invented to aid therapeutic intervention of diseases related to abnormal H2S metabolism. The primary purpose of this review was to provide an overview of the role of H2S in the blood vessel, methods of endogenous production detections and common ion channels used to produce its biological effect describe its benefcial effects.
Hydrogen sulfide (H2S) is a gaseous signaling molecule produced in the body by three enzymes: cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST). H2S is crucial in various physiological processes associated with female mammalian reproduction. These include estrus cycle, oocyte maturation, oocyte aging, ovulation, embryo transport and early embryo development, the development of the placenta and fetal membranes, pregnancy, and the initiation of labor. Despite the confirmed presence of H2S-producing enzymes in all female reproductive tissues, as described in this review, the exact mechanisms of H2S action in these tissues remain in most cases unclear. Therefore, this review aims to summarize the knowledge about the presence and effects of H2S in these tissues and outline possible signaling pathways that mediate these effects. Understanding these pathways may lead to the development of new therapeutic strategies in the field of women’s health and perinatal medicine.
Hydrogen sulfide (H 2 S) is previously described as a potentially lethal toxic gas. However, this gasotransmitter is also endogenously generated by the actions of cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST) in mammalian systems, thus belonging to the family of gasotransmitters after nitric oxide (NO) and carbon monoxide (CO). The physiological or pathological significance of H 2 S has been extensively expanded for decades. Growing evidence has revealed that H 2 S exerts cytoprotective functions in the cardiovascular, nervous and gastrointestinal systems by modulating numerous signaling pathways. With the continuous advancement of microarray and next-generation sequencing technologies, noncoding RNAs (ncRNAs) have gained recognition as key players in human health and diseases due to their considerable potential as predictive biomarkers and therapeutic targets. Coincidentally, H 2 S and ncRNAs are not independent regulators but interact with each other during the development and progression of human diseases. Specifically, ncRNAs might serve as downstream mediators of H 2 S or act on H 2 S-generating enzymes to govern endogenous H 2 S production. The purpose of this review is to summarize interactive regulatory roles of H 2 S and ncRNAs in the initiation and development of various diseases, and explore their potential health and therapeutic benefits. This review will also highlight the importance of crosstalk between H 2 S and ncRNAs in disease therapy.
In this study, we investigated the blood pressure responses of the peripheral bed in vivo after chronic hydrogen sulphide (H2S) inhibition combined with acute nitric oxide (NO) deficiency. We also evaluated the role of endogenously produced H2S in the vasoactive responses of large- and medium-sized arteries in vitro. Changes in integrated blood pressure responses were measured after chronic inhibition of cystathionine-γ-lyase, an enzyme involved in H2S synthesis, with DL-propargylglycine (PPG), and acute inhibition of NO-synthase with nonspecific L-NG-nitro arginine methyl ester (L-NAME), and vasoactive responses of the thoracic aorta (TA) and mesenteric artery (MA) were investigated after acute incubation with PPG. We confirmed that chronic H2S deficiency had no effect on blood pressure, heart trophycity, noradrenaline and H2S donor vasoactive responses but induced renal hypertrophy and decrease in acetylcholine-induced hypotensive and L-NAME-induced hypertensive responses. Acute H2S deficiency led to an increase in basal tone (MA) or active tone (TA), whereas endothelium-dependent vasorelaxation remained unaffected. Long-term administration of PPG revealed a role of endogenous H2S in the bioavailability of endothelial NO in peripheral arteries. When both H2S and NO were lacking, the activation of H2S-independent compensatory mechanisms plays an important role in maintaining the vasodilator responses of the cardiovascular system.
Hydrogen sulfide (H2S), nitric oxide (NO), carbon monoxide (CO), and sulfur dioxide (SO2) were previously considered as toxic gases, but now they are found to be members of mammalian gasotransmitters family. Both H2S and SO2 are endogenously produced in sulfur-containing amino acid metabolic pathway in vivo. The enzymes catalyzing the formation of H2S are mainly CBS, CSE, and 3-MST, and the key enzymes for SO2 production are AAT1 and AAT2. Endogenous NO is produced from L-arginine under catalysis of three isoforms of NOS (eNOS, iNOS, and nNOS). HO-mediated heme catabolism is the main source of endogenous CO. These four gasotransmitters play important physiological and pathophysiological roles in mammalian cardiovascular, nervous, gastrointestinal, respiratory, and immune systems. The similarity among these four gasotransmitters can be seen from the same and/or shared signals. With many studies on the biological effects of gasotransmitters on multiple systems, the interaction among H2S and other gasotransmitters has been gradually explored. H2S not only interacts with NO to form nitroxyl (HNO), but also regulates the HO/CO and AAT/SO2 pathways. Here, we review the biosynthesis and metabolism of the gasotransmitters in mammals, as well as the known complicated interactions among H2S and other gasotransmitters (NO, CO, and SO2) and their effects on various aspects of cardiovascular physiology and pathophysiology, such as vascular tension, angiogenesis, heart contractility, and cardiac protection.
Hydrogen sulfide (H2S) represents the third and the youngest member of the gaseous transmitters family. The dominant effect of H2S on isolated vessels is vasodilation. As the mechanism of H2S‐induced relaxation in human vessels remains unclear, the present study aimed to investigate the effects of H2S donor, sodium hydrosulfide (NaHS), on isolated human saphenous vein (HSV) and to determine the mechanism of action.
Our results showed that NaHS (1 µM – 3 mM) induced a concentration‐dependent relaxation of endothelium‐intact HSV rings pre‐contracted by phenylephrine. Pre‐treatment with L‐NAME, ODQ and KT5823 significantly inhibited NaHS‐induced relaxation, while indomethacin induced partial inhibition. Among K⁺ channels blockers, the combination of apamin and TRAM‐34 significantly affected the relaxation produced by NaHS, while iberiotoxin and glibenclamide only reduced maximal relaxation of HSV. NaHS partially relaxed endothelium‐intact rings pre‐contracted by high K⁺, as well as phenylephrine‐contracted rings in the presence of nifedipine. Additionally, the incubation of HSV rings with NaHS increased NO production. These results demonstrate that NaHS produces the concentration‐ and endothelium‐dependent relaxation of isolated HSV. Vasorelaxation to NaHS probably involves activation of NO/cGMP/PKG pathway and partially prostacyclin. In addition, different K⁺ channels subtypes, especially SKCa and IKCa, as well as BKCa and KATP channels in high concentrations of NaHS, probably participate in the NaHS‐induced vasorelaxation.
Normal pregnancy is associated with dramatic increases in uterine blood flow to facilitate the bidirectional maternal-fetal exchanges of respiratory gases and to provide the sole nutrient support for fetal growth and survival. The mechanism(s) underlying pregnancy-associated uterine vasodilation remains incompletely understood, but this is associated with elevated estrogens that stimulate specific estrogen receptors (ER)-dependent vasodilator production in uterine artery (UA). The classical ERs (ERα and ERβ) and the plasma-bound G protein-coupled ER (GPR30/GPER) are expressed in UA endothelial cells and smooth muscle cells, mediating the vasodilatory effects of estrogens through genomic and/or nongenomic pathways that are likely epigenetically modified. Activation of these three ERs by estrogens enhances endothelial production of nitric oxide (NO) that has been shown to play a key role in uterine vasodilation during pregnancy. However, local blockade of NO biosynthesis only partially attenuate estrogen-induced and pregnancy-associated uterine vasodilation, suggesting mechanisms other than NO exist to mediate uterine vasodilation. In this review, we summarized the literature on the role of NO in ER-mediated mechanisms controlling estrogen-induced and pregnancy-associated uterine vasodilation and our recent work on a "new" UA vasodilator hydrogen sulfide (H2S) that has dramatically changed our view of how estrogens regulate uterine vasodilation in pregnancy.
Hydrogen sulfide (H2S), in addition to nitric oxide and carbon monoxide, is the third gasotransmitter and known to cause relaxation in peripheral arteries. Here we describe a method that allows simultaneous measurement of contractility in arteries mounted in an isometric wire myograph and the concentration of free H2S in the lumen of the artery as well as in the organ bath. This method can be used to directly correlate how much free H2S is needed to cause relaxation, which previously has been difficult to answer as H2S can be found in many different forms.
Isolated tissue chamber bath system and wire myograph were developed for “in vitro” investigation of vasoactive responses on isolated arteries from a variety of animal species and vascular beds. The chapter characterizes the main principles of mechanical measurement of the changes in isometric tension of vascular smooth muscles in isolated rat thoracic aorta and superior mesenteric artery and describes several protocols on how to investigate vasoactive properties of hydrogen sulfide (H2S) from the point of view of its mutual interaction with NO. Several methodological advances, results, and their interpretations in the context of the general knowledge are described. In the protocols the approach on how to study the vasoactive modulatory as well as direct action of H2S and mutual interaction of H2S with nitroso compounds, lipids, and endogenously produced NO is described.
Gasotransmitters are gas molecules produced endogenously in prokaryotic and eukaryotic cells for signalling purposes. This book provides, for the first time, a comprehensive description and systematic look at all gasotransmitters, established or proposed, since their detection in 2002. The content and scope covers the production, metabolism, and signalling roles of gasotransmitters. Conceptual advances, scientific discoveries and newly developed techniques described in this book influence our understanding of fundamental molecular and cellular events in biology and medicine.
This book serves as the state-of-the-art book for undergraduate and graduate students as well as post-doctoral fellows in biomedical disciplines and toxicologists studying the toxic mechanisms of gasotransmitters in the environment. It will also be welcomed by researchers in university and research institutes, government agencies, pharmaceutical and medical instrument industry, and clinical practice.
Carbon monoxide (CO), hydrogen sulfide (H2S), and nitric oxide (NO) constitute endogenous gaseous molecules produced by specific enzymes. These gases are chemically simple, but exert multiple effects and act through shared molecular targets to control both physiology and pathophysiology in the cardiovascular system (CVS). The gases act via direct and/or indirect interactions with each other in proteins such as heme-containing enzymes, the mitochondrial respiratory complex, and ion channels, among others. Studies of the major impacts of CO, H2S, and NO on the CVS have revealed their involvement in controlling blood pressure and in reducing cardiac reperfusion injuries, although their functional roles are not limited to these conditions. In this review, the basic aspects of CO, H2S, and NO, including their production and effects on enzymes, mitochondrial respiration and biogenesis, and ion channels are briefly addressed to provide insight into their biology with respect to the CVS. Finally, potential therapeutic applications of CO, H2S, and NO with the CVS are addressed, based on the use of exogenous donors and different types of delivery systems.
We elucidated the structure and alternative splicing patterns of the rat cystathionine beta-synthase gene. The gene is 20-25 kilobase pairs long, and its coding region is divided into 17 exons. These are alternatively spliced, forming four distinct mRNAs (types I through IV). The predicted open reading frames encode proteins of 61.5, 39, 60, and 52.5 kDa, respectively. Exons 13 and 16 are used alternatively and mutually exclusively. Exon 13 includes a stop codon and encodes the unique carboxyl-terminal sequence found in types II and IV. Exon 16 is present only in type I. Types I and III, which differ by 42 nucleotides (exon 16), are the predominant synthase mRNA forms in rat liver. Seventeen arginine peptides from pure liver synthase matched the deduced amino acid sequences of types I and III. These two polypeptides are detectable in liver extracts; each exhibits enzymatic activity when expressed in transfected Chinese hamster cells. Synthase shows substantial sequence similarity with pyridoxal 5'-phosphate dependent enzymes from lower organisms. Similarity of synthase to Escherichia coli O-acetylserine (thiol)-lyase (cysK) is 52%; E. coli tryptophan synthase beta chain (trpB), 36%; yeast serine deaminase, 33%. Lysine 116 in synthase aligns with the established pyridoxyllysine residue of these enzymes suggesting that it is the pyridoxal 5'-phosphate binding residue.
Hydrogen sulfide (H2S), which is well known as a toxic gas, is produced endogenously from L-cysteine in mammalian tissues. H2S is present at relatively high levels in the brain, suggesting that it has a physiological function. Two other gases, nitric oxide and carbon monoxide, are also endogenously produced and have been proposed as neuronal messengers in the brain. In this work we show the following: (1) an H2S-producing enzyme, cystathionine beta-synthase (CBS), is highly expressed in the hippocampus; (2) CBS inhibitors hydroxylamine and amino-oxyacetate suppress the production of brain H2S; and (3) a CBS activator, S-adenosyl-L-methionine, enhances H2S production, indicating that CBS contributes to the production of endogenous H2S. We also show that physiological concentrations of H2S selectively enhance NMDA receptor-mediated responses and facilitate the induction of hippocampal long-term potentiation. These observations suggest that endogenous H2S functions as a neuromodulator in the brain.
Hydrogen sulfide (H(2)S) is a recently identified endogenous vasodilator in mammals. In steelhead/rainbow trout (Oncorhynchus mykiss, Osteichthyes), H(2)S produces both dose-dependent dilation and a unique dose-dependent constriction. In this study, we examined H(2)S vasoactivity in all vertebrate classes to determine whether H(2)S is universally vasoactive and to identify phylogenetic and/or environmental trends. H(2)S was generated from NaHS and examined in unstimulated and precontracted systemic and, when applicable, pulmonary arteries (PA) from Pacific hagfish (Eptatretus stouti, Agnatha), sea lamprey (Petromyzon marinus, Agnatha), sandbar shark (Carcharhinus milberti, Chondrichthyes), marine toad (Bufo marinus, Amphibia), American alligator (Alligator mississippiensis, Reptilia), Pekin duck (Anas platyrhynchos domesticus, Aves), and white rat (Rattus rattus, Mammalia). In otherwise unstimulated vessels, NaHS produced 1) a dose-dependent relaxation in Pacific hagfish dorsal aorta; 2) a dose-dependent contraction in sea lamprey dorsal aorta, marine toad aorta, alligator aorta and PA, duck aorta, and rat thoracic aorta; 3) a threshold relaxation in shark ventral aorta, dorsal aorta, and afferent branchial artery; and 4) a multiphasic contraction-relaxation-contraction in the marine toad PA, duck PA, and rat PA. Precontraction of these vessels with another agonist did not affect the general pattern of NaHS vasoactivity with the exception of the rat aorta, where relaxation was now dominant. These results show that H(2)S is a phylogenetically ancient and versatile vasoregulatory molecule that appears to have been opportunistically engaged to suit both organ-specific and species-specific homeostatic requirements.
Hydrogen sulfide (H2S) is a naturally occurring gas with potent vasodilator activity. Cystathionine‐γ‐lyase (CSE) and cystathionine‐β‐synthase (CBS) utilize l‐cysteine as substrate to form H2S. Of these two enzymes, cystathionine‐γ‐lyase (CSE) is believed to be the key enzyme that forms H2S in the cardiovascular system. Whilst H2S has been reported to relax precontracted rat arteries in vitro and to lower blood pressure in the rat, its effect in an inflammatory condition such as acute pancreatitis has not previously been reported. In this paper, we report the presence of H2S synthesizing enzyme activity and CSE (as determined by mRNA signal) in the pancreas. Also, prophylactic, as well as therapeutic, treatment with the CSE inhibitor, DL‐propargylglycine (PAG), significantly reduced the severity of caerulein‐induced pancreatitis and associated lung injury, as determined by 1) hyperamylasemia [plasma amylase (U/L) (control, 1204±59); prophylactic treatment: placebo, 10635±305; PAG, 7904±495; therapeutic treatment: placebo, 10427±470; PAG, 7811±428; P<0.05 PAG c.f. placebo; n=24 animals in each group]; 2) neutrophil sequestration in the pancreas [pancreatic myeloperoxidase oxidase (MPO) activity (fold increase over control) (prophylactic treatment: placebo, 5.78±0.63; PAG, 2.97±0.39; therapeutic treatment: placebo, 5.48±0.52; PAG, 3.03±0.47; P<0.05 PAG c.f. placebo; n=24 animals in each group)]; 3) pancreatic acinar cell injury/necrosis; 4) lung MPO activity (fold increase over control) [prophylactic treatment: placebo, 1.99±0.16; PAG, 1.34±0.14; therapeutic treatment: placebo, 2.03±0.12; PAG, 1.41±0.97; P<0.05 PAG c.f. placebo; n=24 animals in each group]; and 5) histological evidence of lung injury. These effects of CSE blockade suggest an important proinflammatory role of H2S in regulating the severity of pancreatitis and associated lung injury and raise the possibility that H2S may exert similar activity in other forms of inflammation.
Hydrogen sulfide (H2S) is synthesized in the body from l‐cysteine by several enzymes including cystathionine‐γ‐lyase (CSE). To date, there is little information about the potential role of H2S in inflammation. We have now investigated the part played by H2S in endotoxin‐induced inflammation in the mouse. E. coli lipopolysaccharide (LPS) administration produced a dose (10 and 20 mg/kg ip)‐ and time (6 and 24 h)‐dependent increase in plasma H2S concentration. LPS (10 mg/kg ip, 6 h) increased plasma H2S concentration from 34.1 ± 0.7 µM to 40.9 ± 0.6 µM (n=6, P<0.05) while H2S formation from added l‐cysteine was increased in both liver and kidney. CSE gene expression was also increased in both liver (94.2±2.7%, n=6, P<0.05) and kidney (77.5±3.2%, n=6, P<0.05). LPS injection also elevated lung (148.2±2.6%, n=6, P<0.05) and kidney (78.8±8.2%, n=6, P<0.05) myeloperoxidase (MPO, a marker of tissue neutrophil infiltration) activity alongside histological evidence of lung, liver, and kidney tissue inflammatory damage. Plasma nitrate/nitrite (NOx) concentration was additionally elevated in a time‐ and dose‐dependent manner in LPS‐injected animals. To examine directly the possible proinflammatory effect of H2S, mice were administered sodium hydrosulfide (H2S donor drug, 14 µmol/kg ip) that resulted in marked histological signs of lung inflammation, increased lung and liver MPO activity, and raised plasma TNF‐α concentration (4.6±1.4 ng/ml, n=6). In contrast, dl‐propargylglycine (CSE inhibitor, 50 mg/kg ip), exhibited marked anti‐inflammatory activity as evidenced by reduced lung and liver MPO activity, and ameliorated lung and liver tissue damage. In separate experiments, we also detected significantly higher (150.5±43.7 µM c.f. 43.8±5.1 µM, n=5, P<0.05) plasma H2S levels in humans with septic shock. These findings suggest that H2S exhibits proinflammatory activity in endotoxic shock and suggest a new approach to the development of novel drugs for this condition.
Hydrogen sulfide (H(2)S) vasoactivity has been observed in isolated vessels from all vertebrate classes, and its effects, which include constriction, dilation, and multiphasic responses, are both species- and vessel-specific. H(2)S is synthesized by mammalian and fish vessels, and because plasma H(2)S titers are also vasoactive in vitro, it is likely that H(2)S is a tonic effector of cardiovascular homeostasis in many vertebrates. Mechanisms of H(2)S vasoactivity in nonmammalian vertebrates have been limited to the trout where the triphasic relaxation-contraction-relaxation includes endothelium-dependent and -independent components, ATP-dependent K(+) channels, and extracellular and intracellular Ca(2+), all independent of cyclic GMP production. The observation that at least some H(2)S constrictory activity has been observed in all vertebrates except sharks suggests that H(2)S may have been an ancestral pressor gasotransmitter. However, the ability of H(2)S to serve as either (or both) an endothelium-independent constrictor or dilator, which is relatively unique among vasoregulatory molecules, is a feature that seems to have been exploited, for unknown reasons, by nearly all vertebrates. Aquatic vertebrates appear particularly vulnerable to H(2)S because of their intrinsically low blood pressure and the potential for increased H(2)S exposure from the environment.
Hydrogen sulfide (H(2)S) functions as a neuromodulator, but whether it modulates visceral perception and pain is unknown. Cystathionine beta-synthase (CBS) and cystathionine-gamma-lyase (CSE) mediate enzymatic generation of H(2)S in mammalian cells. Here we have investigated the role of H(2)S in modulating nociception to colorectal distension, a model that mimics some features of the irritable bowel syndrome. Four graded (0.4-1.6 ml of water) colorectal distensions (CRDs) were produced in conscious rats (healthy and postcolitic), and rectal nociception was assessed by measuring the behavioral response during CRD. Healthy rats were administered with sodium hydrogen sulfide (NaHS) (as a source of H(2)S), L-cysteine, or vehicle. In a second model, we investigated nociception to CRD in rats recovering from a chemically induced acute colitis. We found that CBS and CSE are expressed in the colon and spinal cord. Treating rats with NaHS resulted in a dose-dependent attenuation of CRD-induced nociception with the maximal effect at 60 micromol/kg (p < 0.05). Administration of L-cysteine, a CSE/CBS substrate, reduced rectal sensitivity to CRD (p < 0.05). NaHS-induced antinociception was reversed by glibenclamide, a ATP-sensitive K(+) (K(ATP)) channel inhibitor, and N(omega)-nitro-L-arginine methyl ester hydrochloride (L-NAME), a nitric-oxide (NO) synthase inhibitor. The antinociceptive effect of NaHS was maintained during the resolution of colon inflammation induced by intrarectal administration of a chemical irritant. In summary, these data show that H(2)S inhibits nociception induced by CRD in both healthy and postcolitic rats. This effect is mediated by K(ATP) channels and NO. H(2)S-releasing drugs might be beneficial in treating painful intestinal disorders.
Endogenous H(2)S is synthesized mainly by cystathionine gamma-lyase in the heart. The present study investigated the role of H(2)S in cardioprotection induced by ischemic preconditioning. We have examined the effect of endogenous H(2)S and exogenous application of NaHS (H(2)S donor) on cardiac rhythm in the isolated rat heart subjected to low-flow ischemia insults as well as cell viability and function in isolated myocytes exposed to simulated ischemia solution. Preconditioning with NaHS (SP) or ischemia (IP) for three cycles (3 min each cycle separated by 5 min of recovery) significantly decreased the duration and severity of ischemia/reperfusion-induced arrhythmias in the isolated heart while increasing cell viability and the amplitude of electrically induced calcium transients after ischemia/reperfusion in cardiac myocytes. Both IP and SP also significantly attenuated the decreased H(2)S production during ischemia. Moreover, decreasing endogenous H(2)S production significantly attenuated the protective effect of IP in both the isolated heart and isolated cardiac myocytes. Blockade of protein kinase C with chelerythrine or bisindolylmaleimide I as well as ATP-sensitive K(+) (K(ATP)) channel with glibenclamide (a nonselective K(ATP) blocker) and HMR-1098 (1-[[5-[2-(5-Chloro-o-anisamido)ethyl]-2-methoxyphenyl]sulfonyl]-3-methylthiourea) (a sarcolemmal K(ATP) channel blocker) reversed the cardioprotection induced by SP or IP. However, blockade of mitochondrial K(ATP) channels with 5-hydroxydecanoic acid had no effect on the cardioprotection of SP, suggesting that, unlike the mechanism involved in IP, mitochondrial K(ATP) channels most probably do not play a major role in the cardioprotection of SP. Our findings suggest that endogenous H(2)S contributes to cardioprotection induced by IP, which effect may involve protein kinase C and sarcolemmal K(ATP) channels.
The sulphonylurea drug glibenclamide is a widely used inhibitor of the cystic fibrosis transmembrane conductance regulator (CFTR). To investigate how glibenclamide inhibits CFTR, we studied CFTR Cl ⁻ channels using excised inside‐out membrane patches from cells expressing wild‐type human CFTR.
Addition of glibenclamide (10–100 μM) to the intracellular solution caused a concentration‐dependent decrease in the open time of CFTR Cl ⁻ channels, but closed times did not change. This suggests that glibenclamide is an open‐channel blocker of CFTR.
Glibenclamide is a weak organic acid. Acidification of the intracellular solution relieved glibenclamide inhibition of CFTR, suggesting that the anionic form of glibenclamide inhibits CFTR.
To begin to identify the glibenclamide binding site in CFTR, we investigated whether glibenclamide competes with either MgATP or Cl ⁻ ions for a common binding site. Glibenclamide inhibition of CFTR was unaffected by nucleotide‐dependent stimulation of CFTR, suggesting that glibenclamide and intracellular MgATP interact with CFTR at distinct sites.
Glibenclamide inhibition of CFTR was voltage dependent and enhanced when the external Cl ⁻ concentration was decreased. The data suggest that glibenclamide and Cl ⁻ ions may compete for a common binding site located within a large intracellular vestibule that is part of the CFTR pore.
The information available on the biological activity of hydrogen sulfide has been examined for present status of critical results pertaining to the toxicity of hydrogen sulfide. This review of the literature is intended as an evaluative report rather than an annotated bibliography of all the source material examined on hydrogen sulfide. The information was selected as it might relate to potential toxic effects of hydrogen sulfide to man and summarized, noting information gaps that may require further investigation. Several recommendations are listed for possible consideration for either toxicological research or additional short- and long-term tests. Two bibliographies have been provided to assist in locating references considered in this report: (1) literature examined but not cited and (2) reference citations. The majority of the references in the first bibliography were considered peripheral information and less appropriate for inclusion in this report.
The contribution of cystathionine gamma-lyase, cystathionine beta-synthase and cysteine aminotransferase coupled to 3-mercaptopyruvate sulphurtransferase to cysteine desulphhydration in rat liver and kidney was assessed with four different assay systems. Cystathionine gamma-lyase and cystathionine beta-synthase were active when homogenates were incubated with 280 mM-L-cysteine and 3 mM-pyridoxal 5'-phosphate at pH 7.8. Cysteine aminotransferase in combination with 3-mercaptopyruvate sulphurtransferase catalysed essentially all of the H2S production from cysteine at pH 9.7 with 160 mM-L-cysteine, 2 mM-pyridoxal 5'-phosphate, 3 mM-2-oxoglutarate and 3 mM-dithiothreitol. At more-physiological concentrations of cysteine (2 mM) cystathionine gamma-lyase and cystathionine beta-synthase both appeared to be active in cysteine desulphhydration, whereas the aminotransferase pathway did not. The effect of inhibition of cystathionine gamma-lyase by a suicide inactivator, propargylglycine, in the intact rat was also investigated; there was no significant effect of propargylglycine administration on the urinary excretion of total 35S, 35SO4(2-) or [35S]taurine formed from labelled dietary cysteine.
Hydrogen sulfide (H2S), which is well known as a toxic gas, is produced endogenously in mammalian tissues from L-cysteine mainly by two pyridoxal-5'-phosphate-dependent enzymes, cystathionine beta-synthetase and cystathionine gamma-lyase. Recently, we showed that cystathionine beta-synthetase in the brain produces H2S, and that H2S facilitates the induction of hippocampal long-term potentiation by enhancing NMDA receptor activity. Here we show that mRNA for another H2S producing enzyme, cystathionine gamma-lyase, is expressed in the ileum, portal vein, and thoracic aorta. The ileum also expresses cystathionine beta-synthetase mRNA. These tissues produce H2S, and this production is blocked by cystathionine beta-synthetase and cystathionine gamma-lyase specific inhibitors. Although exogenously applied H2S alone relaxed these smooth muscles, much lower concentrations of H2S greatly enhanced the smooth muscle relaxation induced by NO in the thoracic aorta. These observations suggest that the endogenous H2S may regulate smooth muscle tone in synergy with NO.
1. The sulphonylurea drug glibenclamide is a widely used inhibitor of the cystic fibrosis transmembrane conductance regulator (CFTR). To investigate how glibenclamide inhibits CFTR, we studied CFTR Cl- channels using excised inside-out membrane patches from cells expressing wild-type human CFTR. 2. Addition of glibenclamide (10-100 microM) to the intracellular solution caused a concentration-dependent decrease in the open time of CFTR Cl- channels, but closed times did not change. This suggests that glibenclamide is an open-channel blocker of CFTR. 3. Glibenclamide is a weak organic acid. Acidification of the intracellular solution relieved glibenclamide inhibition of CFTR, suggesting that the anionic form of glibenclamide inhibits CFTR. 4. To begin to identify the glibenclamide binding site in CFTR, we investigated whether glibenclamide competes with either MgATP or Cl- ions for a common binding site. Glibenclamide inhibition of CFTR was unaffected by nucleotide-dependent stimulation of CFTR, suggesting that glibenclamide and intracellular MgATP interact with CFTR at distinct sites. 5. Glibenclamide inhibition of CFTR was voltage dependent and enhanced when the external Cl- concentration was decreased. The data suggest that glibenclamide and Cl- ions may compete for a common binding site located within a large intracellular vestibule that is part of the CFTR pore.
Hydrogen sulfide (H(2)S) is produced endogenously from l-cysteine in mammalian tissues, and may function as a neuromodulator in the brain as well as a tone regulator in smooth muscle. H(2)S is present at relatively high levels in the brain, and cystathionine beta-synthase (CBS), which is highly expressed in the hippocampus, is involved in the production of brain H(2)S. Physiological concentrations of H(2)S selectively enhance NMDA receptor-mediated currents and facilitate the induction of hippocampal long-term potentiation (LTP). The NMDA receptor subunits are directly phosphorylated at specific sites by protein kinase A (PKA), resulting in the activation of NMDA-receptor-mediated excitatory postsynaptic currents. PKA activation is also observed in the induction of LTP. Here we show that physiological concentrations of H(2)S increase the production of cAMP in primary cultures of brain cells, neuronal and glial cell lines, and Xenopus oocytes. NMDA receptors expressed on Xenopus oocyte membrane are modulated by H(2)S. This modulation by H(2)S is specifically inhibited by adenylyl cyclase-specific inhibitor MDL-12, 330A. The present findings provide a mechanism for the previous observation that H(2)S modulates NMDA receptors and enhances the induction of LTP.
Hydrogen sulfide (H(2)S) has been traditionally viewed as a toxic gas. It is also, however, endogenously generated from cysteine metabolism. We attempted to assess the physiological role of H(2)S in the regulation of vascular contractility, the modulation of H(2)S production in vascular tissues, and the underlying mechanisms. Intravenous bolus injection of H(2)S transiently decreased blood pressure of rats by 12- 30 mmHg, which was antagonized by prior blockade of K(ATP) channels. H(2)S relaxed rat aortic tissues in vitro in a K(ATP) channel-dependent manner. In isolated vascular smooth muscle cells (SMCs), H(2)S directly increased K(ATP) channel currents and hyperpolarized membrane. The expression of H(2)S-generating enzyme was identified in vascular SMCs, but not in endothelium. The endogenous production of H(2)S from different vascular tissues was also directly measured with the abundant level in the order of tail artery, aorta and mesenteric artery. Most importantly, H(2)S production from vascular tissues was enhanced by nitric oxide. Our results demonstrate that H(2)S is an important endogenous vasoactive factor and the first identified gaseous opener of K(ATP) channels in vascular SMCs.
H(2)S is endogenously generated in vascular smooth muscle cells. The signal transduction pathways involved in the vascular effects of H(2)S have been unclear and were investigated in the present study. H(2)S induced a concentration-dependent relaxation of rat aortic tissues that was not affected by vascular denervation. The vasorelaxant potency of H(2)S was attenuated by the removal of the endothelium. Similarly, the blockade of nitric oxide synthase or the coapplication of the Ca(2+)-dependent K(+) channel blockers apamin and charybdotoxin reduced the H(2)S-induced relaxation of the endothelium-intact aortic tissues. Sodium nitroprusside (SNP)-induced relaxation was completely abolished by either 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ) or NS- 2028, two soluble guanylate cyclase inhibitors. Instead of inhibition, ODQ and NS-2028 potentiated the H(2)S-induced vasorelaxation, which was suppressed by superoxide dismutase. The vasorelaxant effect of H(2)S was also significantly attenuated when Ca(2+)-free bath solution was used. Finally, pretreatment of aortic tissues with H(2)S reduced the relaxant response of vascular tissues to SNP. Our results demonstrate that the vascular effect of H(2)S is partially mediated by a functional endothelium and dependent on the extracellular calcium entry but independent of the activation of the cGMP pathway.
The present study intended to investigate whether the impaired H2S synthase/H2S pathway is associated with hypertension.
Hypertension in Wistar rats was induced by the oral administration of the l-arginine analog, NG-nitro-l-arginine methyl ester (l-NAME) in their drinking water for a period of 6 weeks. The control rats were given plain tap water only. Sodium hydrosulfide (NaHS) was given by intraperitoneal injection to both the control group and the l-NAME-treated group. The systolic BP (blood pressure) was measured by a tail-cuff method using a pulse transducer. Plasma hydrogen sulfide (H2S), and H2S generation by thoracic aorta and superior mesenteric artery, were determined. In addition, the activity of cystathionine-gamma-lyase (CSE) in thoracic aorta and superior mesenteric artery, most responsible for H2S production, was also measured. Competitive reverse transcriptase-polymerase chain reaction (RT-PCR) was used to determine CSE mRNA in thoracic aorta.
l-NAME caused a time-dependent elevation of systolic BP. The heart-to-body weight ratio of l-NAME-treated rats was 27% higher than that of controls. The systolic BP in the NaHS-treated l-NAME group was significantly decreased, by 19% (P < 0.01), in comparison with the l-NAME group. The heart-to-body weight ratio decreased significantly by 12%. l-NAME inhibited CSE gene expression significantly. The inhibition of H2S generation and CSE activity by l-NAME was greatly attenuated in the NaHS-treated l-NAME group. However, there was no significant difference in nitric oxide (NO) generation between the l-NAME group and the NaHS-treated l-NAME group.
In summary, dysfunction of the vascular H2S synthase/H2S pathway was found in l-NAME-induced hypertensive rats. Exogenous H2S effectively prevented the development of hypertension induced by l-NAME. These findings suggest that the H2S synthase/H2S pathway participates in hypertension.
Bearing the public image of a deadly "gas of rotten eggs," hydrogen sulfide (H2S) can be generated in many types of mammalian cells. Functionally, H2S has been implicated in the induction of hippocampal long-term potentiation, brain development, and blood pressure regulation. By acting specifically on KATP channels, H2S can hyperpolarize cell membranes, relax smooth muscle cells, or decrease neuronal excitability. The endogenous metabolism and physiological functions of H2S position this gas well in the novel family of endogenous gaseous transmitters, termed "gasotransmitters." It is hypothesized that H2S is the third endogenous signaling gasotransmitter, besides nitric oxide and carbon monoxide. This positioning of H2S will open an exciting field-H2S physiology-encompassing realization of the interaction of H2S and other gasotransmitters, sulfurating modification of proteins, and the functional role of H2S in multiple systems. It may shed light on the pathogenesis of many diseases related to the abnormal metabolism of H2S.
Previous work has shown that the endogenous cystathionine gamma-synthase (CSE)/hydrogen sulfide (H(2)S) pathway participates in the regulation of cardiac contraction. We hypothesized that the pathway might participate in the pathophysiological regulation of ischemic heart disease. Isoproterenol injection of rat hearts induced a myocardial ischemic injury model, with reduced myocardial and plasma H(2)S levels, decreased CSE activity, and upregulated CSE gene expression. Exogenous administration of the H(2)S donor NaHS reduced the mortality rate; increased left-ventricular pressure development and left-ventricular-end systolic pressure; and decreased left-ventricular-end diastolic pressure (LVEDP) and subendocardial necrosis, capillary dilatation, leukocytic infiltration, fibroblast swelling, and fibroblastic hyperplasia. As well, production of lipid peroxidation, including myocardial malondialdehyde (MDA), and plasma MDA and conjugated diene, was reduced. Oxidative stress injury is an important mechanism of isoproterenol-induced myocardial injury. In vitro experiments revealed that NaHS might antagonize myocyte MDA production by oxygen-free radicals and that NaHS directly scavenged hydrogen peroxide and superoxide anions. Our results suggest that the endogenous CSE/H(2)S pathway contributes to the pathogenesis of isoproterenol-induced myocardial injury. Administration of exogenous H(2)S effectively protects myocytes and contractile activity, at least by its direct scavenging of oxygen-free radicals and reducing the accumulation of lipid peroxidations.
Hydrogen sulfide (H2S) has been shown recently to function as an important gasotransmitter. The present study investigated the vascular effects of H2S, both exogenously applied and endogenously generated, on resistance mesenteric arteries of rats and the underlying mechanisms. Both H2S and NaHS evoked concentration-dependent relaxation of in vitro perfused rat mesenteric artery beds (MAB). The sensitivity of MAB to H2S (EC50, 25.2 +/- 3.6 microM) was about fivefold higher than that of rat aortic tissues. Removal of endothelium or coapplication of charybdotoxin and apamin to endothelium-intact MAB significantly reduced the vasorelaxation effects of H2S. The H2S-induced relaxation of MAB was partially mediated by ATP-sensitive K+ (KATP) channel activity in vascular smooth muscle cells. Pinacidil (EC50, 1.7 +/- 0.1 microM, n=6) mimicked, but glibenclamide (10 microM, n=6) suppressed, the vasorelaxant effect of H2S. KATP channel currents in isolated mesenteric artery smooth muscle cells were significantly augmented by H2S. L-cysteine, a substrate of cystathionine-gamma-lyase (CSE), at 1 mM increased endogenous H2S production by sixfold in rat mesenteric artery tissues and decreased contractility of MAB. DL-propargylglycine (a blocker of CSE) at 10 microM abolished L-cysteine-dependent increase in H2S production and relaxation of MAB. Our results demonstrated a tissue-specific relaxant response of resistance arteries to H2S. The stimulation of KATP channels in vascular smooth muscle cells and charybdotoxin/apamin-sensitive K+ channels in vascular endothelium by H2S represents important cellular mechanisms for H2S effect on MAB. Our study also demonstrated that endogenous CSE can generate sufficient H2S from exogenous L-cysteine to cause vasodilation. Future studies are merited to investigate direct contribution of endogenous H2S to regulation of vascular tone.
Glibenclamide, a potent cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel blocker, is frequently used to study function and regulation of CFTR Cl(-) channels. In this study, the effects of glibenclamide on intracellular Na(+) concentration ([Na(+)](i)), contraction, Ca(2+) transient, and membrane potential were investigated in isolated guinea pig ventricular myocytes. Glibenclamide increased [Na(+)](i) and decreased contraction and Ca(2+) transient. However, glibenclamide did not change membrane potential. To determine whether inhibition of Na(+)-K(+) pumps and L-type Ca(2+) channels is responsible for the increase of [Na(+)](i) and the decrease of contraction, we tested the effects of glibenclamide on Na(+)-K(+) pump current and L-type Ca(2+) current (I(Ca,L)). Glibenclamide decreased Na(+)-K(+) pump current and I(Ca,L) in a concentration-dependent manner. In the presence of Cl(-) channel inhibitors, glibenclamide depolarized diastolic membrane potential and reduced action potential duration. This result suggests that the reason for lack of effect of glibenclamide on membrane potential might be due to its combined inhibitory effects on the Na(+)-K(+) pump, the L-type Ca(2+) channel, and Cl(-) channels, which may have opposing effects on membrane potential. These results indicate that glibenclamide increases [Na(+)(i)] by inhibiting the Na(+)-K(+) pump and decreases contraction and Ca(2+) transient, in addition, by blocking the L-type Ca(2+) channel.
We observed recently that elevated plasma cysteine levels are associated with poor clinical outcome in acute stroke patients. In a rat stroke model, cysteine administration increased the infarct volume apparently via its conversion to hydrogen sulfide (H2S). We therefore investigated the effects of H2S and the inhibition of its formation on stroke.
Cerebral ischemia was studied in a rat stroke model created by permanent occlusion of the middle cerebral artery (MCAO). The resultant infarct volume was measured 24 hours after occlusion.
Administration of sodium hydrosulfide (NaHS, an H2S donor) significantly increased the infarct volume after MCAO. The NaHS-induced increase in infarct volume was abolished by the administration of dizolcilpine maleate (an N-methyl-d-aspartate receptor channel blocker). MCAO caused an increase in H2S level in the lesioned cortex as well as an increase in the H2S synthesizing activity. Administration of 4 different inhibitors of H2S synthesis reduced MCAO-induced infarct volume dose dependently. The potency of these inhibitors in effecting neuroprotection in vivo appeared to parallel their potency as inhibitors of H2S synthesis in vitro. It also appeared that most of the H2S synthesizing activity in the cortex results from the action of cystathionine beta-synthase.
The present results strongly suggest that H2S plays a part in cerebral ischemic damage after stroke. Inhibition of H2S synthesis should be investigated for its potential as a novel neuroprotective stroke therapy.
This review focuses on two gaseous cellular messenger molecules, CO and H2S, that are involved in cerebrovascular flow regulation. CO is a dilatory mediator in active hyperemia, autoregulation, hypoxic dilation, and counteracting vasoconstriction. It is produced from heme by a constitutively expressed enzyme [heme oxygenase (HO)-2] expressed highly in the brain and by an inducible enzyme (HO-1). CO production is regulated by controlling substrate availability, HO-2 catalytic activity, and HO-1 expression. CO dilates arterioles by binding to heme that is bound to large-conductance Ca2+-activated K+ channels. This binding elevates channel Ca2+ sensitivity, that increases coupling of Ca2+ sparks to large-conductance Ca2+-activated K+ channel openings and, thereby, hyperpolarizes the vascular smooth muscle. In addition to dilating blood vessels, CO can either inhibit or accentuate vascular cell proliferation and apoptosis, depending on conditions. H2S may also function as a cerebrovascular dilator. It is produced in vascular smooth muscle cells by hydrolysis of l-cysteine catalyzed by cystathione gamma-lyase (CSE). H2S dilates arterioles at physiologically relevant concentrations via activation of ATP-sensitive K+ channels. In addition to dilating blood vessels, H2S promotes apoptosis of vascular smooth muscle cells and inhibits proliferation-associated vascular remodeling. Thus both CO and H2S modulate the function and the structure of circulatory system. Both the HO-CO and CSE-H2S systems have potential to interact with NO and prostanoids in the cerebral circulation. Much of the physiology and biochemistry of HO-CO and CSE-H2S in the cerebral circulation remains open for exploration.
The gaseous mediators hydrogen sulphide (H2S) and nitric oxide (*NO) are synthesised in the body from L-cysteine and L-arginine, respectively. In the cardiovascular system, *NO is an important regulator of vascular tone and its over- or under-production has been linked to a variety of diseases. The physiological significance of H2S is not yet clear but, like *NO, it exhibits vasodilator activity and may play a part in septic and haemorrhagic shock, hypertension, regulation of cardiac contractility, and in inflammation. To date, there have been no reports of a chemical interaction between H2S and *NO. Here we show that incubation of the H2S donor, sodium hydrosulphide, with a range of *NO donors and *NO gas in vitro leads to the formation of a nitrosothiol molecule as determined by a combination of techniques; electron paramagnetic resonance, amperometry, and measurement of nitrite. We further show that this nitrosothiol did not induce cGMP accumulation in cultured RAW264.7 cells unless *NO was released with Cu2+. Finally, using liver homogenates from LPS treated rats we present evidence for the endogenous formation of this nitrosothiol. These findings provide the first evidence for the formation of a novel nitrosothiol generated by reaction between H2S and *NO. We propose that generation of this nitrosothiol in the body may regulate the physiological effects of both *NO and H2S.
Hydrogen sulfide (H(2)S) and nitric oxide (NO) are endogenously synthesized from l-cysteine and l-arginine, respectively. They might constitute a cooperative network to regulate their effects. In this study, we investigated whether H(2)S could affect NO production in rat vascular smooth muscle cells (VSMCs) stimulated with interleukin-1beta (IL-1beta). Although H(2)S by itself showed no effect on NO production, it augmented IL-beta-induced NO production and this effect was associated with increased expression of inducible NO synthase (iNOS) and activation of nuclear factor (NF)-kappaB. IL-1Beta activated the extracellular signal-regulated kinase 1/2 (ERK1/2), and this activation was also enhanced by H(2)S. Inhibition of ERK1/2 activation by the selective inhibitor U0126 inhibited IL-1beta-induced NF-kappaB activation, iNOS expression, and NO production either in the absence or presence of H(2)S. Our findings suggest that H(2)S enhances NO production and iNOS expression by potentiating IL-1beta-induced NF-kappaB activation through a mechanism involving ERK1/2 signaling cascade in rat VSMCs.
Hydrogen sulfide (H(2)S), a regulatory gaseous molecule that is endogenously synthesized by cystathionine gamma-lyase (CSE) and/or cystathionine beta-synthase (CBS) from L-cysteine (L-Cys) metabolism, is a putative vasodilator, and its role in nitric oxide (NO) production is unexplored. Here, we show that at noncytotoxic concentrations, H(2)S was able to inhibit NO production and inducible NO synthase (iNOS) expression via heme oxygenase (HO-1) expression in RAW264.7 macrophages stimulated with lipopolysaccharide (LPS). Both H(2)S solution prepared by bubbling pure H(2)S gas and NaSH, a H(2)S donor, dose dependently induced HO-1 expression through the activation of the extracellular signal-regulated kinase (ERK). Pretreatment with H(2)S or NaHS significantly inhibited LPS-induced iNOS expression and NO production. Moreover, NO production in LPS-stimulated macrophages that are expressing CSE mRNA was significantly reduced by the addition of L-Cys, a substrate for H(2)S, but enhanced by the selective CSE inhibitor beta-cyano-L-alanine but not by the CBS inhibitor aminooxyacetic acid. While either blockage of HO activity by the HO inhibitor, tin protoporphyrin IX, or down-regulation of HO-1 expression by HO-1 small interfering RNA (siRNA) reversed the inhibitory effects of H(2)S on iNOS expression and NO production, HO-1 overexpression produced the same inhibitory effects of H(2)S. In addition, LPS-induced nuclear factor (NF)-kappaB activation was diminished in RAW264.7 macrophages preincubated with H(2)S. Interestingly, the inhibitory effect of H(2)S on NF-kappaB activation was reversed by the transient transfection with HO-1 siRNA, but was mimicked by either HO-1 gene transfection or treatment with carbon monoxide (CO), an end product of HO-1. CO treatment also inhibited LPS-induced NO production and iNOS expression via its inactivation of NF-kappaB. Collectively, our results suggest that H(2)S can inhibit NO production and NF-kappaB activation in LPS-stimulated macrophages through a mechanism that involves the action of HO-1/CO.
Hydrogen sulfide, like nitric oxide, was best known as a toxic pollutant before becoming recognized as a key regulator of several physiologic processes. In recent years, evidence has accumulated to suggest important roles for hydrogen sulfide as a mediator of several aspects of gastrointestinal and liver function. Moreover, alterations in hydrogen sulfide production could contribute to disorders of the gastrointestinal tract and liver. For example, nonsteroidal anti-inflammatory drugs can reduce production of hydrogen sulfide in the stomach, and this has been shown to contribute to the generation of mucosal injury. Hydrogen sulfide has also been shown to play a key role in modulation of visceral hyperalgesia. Inhibitors of hydrogen sulfide synthesis and drugs that can generate safe levels of hydrogen sulfide in vivo have been developed and are permitting interventional studies in experimental models and, in the near future, humans.
The aim of these experiments was to evaluate the significance of the chemical reaction between hydrogen sulphide (H2S) and nitric oxide (NO) for the control of vascular tone.
The effect of sodium hydrosulphide (NaHS; H2S donor) and a range of NO donors, such as sodium nitroprusside (SNP), either alone or together, was determined using phenylephrine (PE)-precontracted rat aortic rings and on the blood pressure of anaesthetised rats.
Mixing NaHS with NO donors inhibited the vasorelaxant effect of NO both in vitro and in vivo. Low concentrations of NaHS or H2S gas in solution reversed the relaxant effect of acetylcholine (ACh, 400 nM) and histamine (100 microM) but not isoprenaline (400 nM). The effect of NaHS on the ACh response was antagonized by CuSO(4) (200 nM) but was unaffected by glibenclamide (10 microM). In contrast, high concentrations of NaHS (200-1600 microM) relaxed aortic rings directly, an effect reduced by glibenclamide but unaffected by CuSO4. Intravenous infusion of a low concentration of NaHS (10 micromol kg(-1) min(-1)) into the anaesthetized rat significantly increased mean arterial blood pressure. L-NAME (25 mg kg(-1), i.v.) pretreatment reduced this effect.
These results suggest that H2S and NO react together to form a molecule (possibly a nitrosothiol) which exhibits little or no vasorelaxant activity either in vitro or in vivo. We propose that a crucial, and hitherto unappreciated, role of H2S in the vascular system is the regulation of the availability of NO.
H(2)S-induced vasorelaxation and under-lying cellular and molecular mechanisms
- W Zhao
- R Wang
Zhao, W., Wang, R., 2002. H(2)S-induced vasorelaxation and under-lying cellular and molecular mechanisms. Am. J. Physiol. Heart Circ. Physiol. 283 (2), H474–H480.
The role of hydrogen sulfide generation in the pathogenesis of hypertension in rats induced by inhibition of nitric oxide synthase
- Zhong