Content uploaded by Bin Geng
Author content
All content in this area was uploaded by Bin Geng
Content may be subject to copyright.
Endogenous Hydrogen Sulfide Regulates
Pulmonary Artery Collagen Remodeling in
Rats with High Pulmonary Blood Flow
XIAOHUI LI,* HONGFANG JIN,* GENG BIN,LIWANG,àCHAOSHU TANG,AND JUNBAO DU*
,1
*Department of Pediatrics, Peking University First Hospital and Key Laboratory of Molecular
Cardiovascular Sciences, Ministry of Education, Beijing 100034, People’s Republic of China;
Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing
100034, People’s Republic of China; and àDepartment of Scientific Research, Peking University Health
Science Center, Beijing 100034, People’s Republic of China
The mechanisms responsible for the structural remodeling of
pulmonary vasculature induced by increased pulmonary blood
flow are not fully understood. This study explores the effect of
endogenous hydrogen sulfide (H
2
S), a novel gasotransmitter, on
collagen remodeling of the pulmonary artery in rats with high
pulmonary blood flow. Thirty-two Sprague-Dawley rats were
randomly divided into sham, shunt, sham1PPG (D,L-propargyl-
glycine, an inhibitor of cystathionine-c-lyase), and shunt1PPG
groups. After 4 weeks of shunting, the relative medial thickness
(RMT) of pulmonary arteries and H
2
S concentration in lung
tissues were investigated. Collagen I and collagen III were
evaluated by hydroxyproline assay, sirius-red staining, and
immunohistochemistry. Pulmonary artery matrix metalloprotein-
ase-13 (MMP-13), tissue inhibitor of metalloproteinase-1 (TIMP-
1), and connective tissue growth factor (CTGF) were evaluated
by immunohistochemistry. After 4 weeks of aortocaval shunt-
ing, resulting in an elevation of lung tissue H
2
S to 116.4%, rats
exhibited collagen remodeling and increased CTGF expression
in the pulmonary arteries. Compared with those of the shunt
group, lung tissue H
2
S production was lowered by 23.4%, RMT
of the pulmonary artery further increased by 39.5%, pulmonary
artery collagen accumulation became obvious, and pulmonary
artery CTGF expression elevated (P<0.01) in the shunted rats
treated with PPG. However, pulmonary artery MMP-13 and TIMP-
1 expressions decreased significantly in rats of shunt1PPG
group (P<0.01). This study suggests that endogenous H
2
S
exerts an important regulatory effect on pulmonary collagen
remodeling induced by high pulmonary blood flow. Exp Biol Med
234:504–512, 2009
Key words: hydrogen sulfide; collagen; pulmonary artery; inhibitor of
metalloproteinase-1 (TIMP-1); matrix metalloproteinase-13 (MMP-
13)
Introduction
Congenital heart disease (CHD) is the most common
heart disease in childhood. It is often characterized by
increased pulmonary blood flow in those with a left-to-right
shunt. This increased blood flow results in vascular injury
and pulmonary hypertension during the course of the
disease. The mechanisms responsible for structural remod-
eling induced by increased pulmonary blood flow are not
fully understood. Collagen accumulation is one of the
important factors in the development of vascular remodeling
and pulmonary hypertension. The regulation of pulmonary
hypertension has also been indicated to be associated with
the role of a novel gasotransmitter, hydrogen sulfide (H
2
S),
which plays a part similar to nitric oxide (NO) and carbon
monoxide (CO) in the relaxation of blood vessels (1–5).
Based on the above evidence, we performed the present
study to investigate the possible changes and roles of
endogenous H
2
S in collagen remodeling in rats with high
pulmonary blood flow.
Materials and Methods
Animal Model of High Pulmonary Blood Flow.
Experiments were conducted in accordance with the Guide
to The Care and Use of Experimental Animals issued by the
Ministry of Health of the People’s Republic of China. Male
Sprague-Dawley rats were provided by the Animal Research
Center of Peking University First Hospital. The rats were
This work was supported by Natural Science Foundation of Beijing, P. R. China
(7072082), National Natural Science Foundation of China (30425010, 30821001,
30801251, 30630031, 30872787), Grant of Ministry of Education, China
(20070001702), and State Major Basic Research Project of China (2006CB503807).
1
To whom correspondence should be addressed at Department of Pediatrics, Peking
University First Hospital, Xi-An Men Street No. 1, West District, Beijing, 100034,
People’s Republic of China. E-mail: junbaodu@ht.rol.cn.net
Received July 28, 2008.
Accepted January 30, 2009.
504
DOI: 10.3181/0807-RM-230
1535-3702/09/2345-0504$15.00
Copyright Ó2009 by the Society for Experimental Biology and Medicine
kept in a temperature-controlled room with a 12 hour light-
dark cycle. Tap water and rat chow were provided ad
libitum. The animal model of the left-to-right shunt was
created according to the method described by Garcia and
Diebold (6) with minor modifications (7). Briefly, 32 male
Sprague-Dawley rats, weighing 120–140 g, were randomly
divided into shunt (n¼8), shuntþpropargylglycine (PPG, an
inhibitor of cystathionine-c-lyase) (n¼8), sham (n¼8), and
shamþPPG (n¼8) groups. We anesthetized rats in the shunt
and shuntþPPG groups with 0.25% pentobarbital sodium
(40 mg/kg, intraperitoneal injection). We exposed the
abdominal aorta and inferior vena cava, and then placed a
bulldog vascular clamp across the aorta caudal to the left
renal artery. We punctured the aorta at the union of the
segment two-thirds caudal to the renal artery and one-third
cephalic to the aortic bifurcation with an 18-gauge
disposable needle. Then, the needle was slowly withdrawn
and a 9–0 silk thread was used to stitch the puncture of the
abdominal wall. In the sham and shamþPPG groups, rats
underwent the same experimental protocol as mentioned
above except for the shunting procedure. We injected rats in
the shuntþPPG and shamþPPG groups intraperitoneally
with PPG at 37.5 mg/kg/d for 4 weeks (8). We injected rats
in the shunt and sham groups with the same volume of
physiological saline.
Measurement of Oxygen Saturation. At 4 weeks
of the experiment, we weighed and anesthetized the animals
with pentobarbital sodium (40 mg/kg, intraperitoneal
injection). We analyzed blood samples (0.5 ml) obtained
from the pulmonary artery, external carotid artery, and
jugular vein using a GASTAT-3 Blood Gas Analysis
Apparatus. The ratio Qp/Qs was calculated as an indicator
of pulmonary and systemic blood flow. Qp/Qs was
calculated by the formula: Qp/Qs ¼[oxygen saturation of
aorta (%) oxygen saturation of jugular vena cava (%)] /
[oxygen saturation of pulmonary vein (%) oxygen
saturation of pulmonary artery (%)]. When the oxygen
saturation of the aorta was .95%, we regarded the oxygen
saturation of the pulmonary vein as 100%. When the oxygen
saturation of the aorta was ,95%, we regarded the oxygen
saturation of the pulmonary vein as 95%.
The right side of the lung tissue was removed and
quickly frozen in liquid nitrogen, then stored at 808C for
homogenate. The left lower part of lung tissue was removed
and post-fixed in 10% (wt/vol) paraformaldehyde.
Measurement of H
2
S in Lung Tissue. We
homogenized lung tissue in a 10-fold volume (w/v) of an
ice-cold potassium phosphate buffer (pH ¼6.8). The
reaction was performed in a 25-ml Erlenmeyer Pyrex flask.
We used cryovial test tubes (2 ml) as the center wells, each
containing 1 M NaOH of 0.5 ml. The reaction mixture
contained lung tissue homogenate and 1 M HCL in a ratio of
1:5. We flushed the flasks containing reaction mixture and
central wells with N
2
for 30 seconds before sealing with a
double layer of parafilm. The reaction was initiated by
transferring the flasks from ice to a shaking water bath at
378C. After incubation at 378C for 4 h, we transferred the
contents of the central wells to 10-ml beakers, each
containing 0.5 ml of antioxidant solution. Subsequently,
the solution was measured with a sulfide-sensitive electrode
(PXS-270, Shanghai, China) to calculate the lung tissue H
2
S
against a standard curve.
Morphological Analysis of Small Pulmonary
Arteries. We mounted fixed lung tissue in paraffin, and
sectioned it at 4 lm thickness. We then stained the elastic
fiber according to the modified Weigert’s method and
counterstained with Van Gieson solution. We performed
morphological analysis using a Video-Linked Microscope
Digitizing Board System (Leica Q550CW, Germany). Only
vessels showing clearly defined external and internal elastic
lamina were used in the analysis. The relative medial
thickness (RMT) was calculated according to Barth’s
methods (9).
Hydroxyproline Assay of Lung Tissue. Lung
tissue homogenate was dehydrated in 0.2 ml of 6 nmol/L
HCl (14 hours). The pH of the samples was adjusted with 6
nmol/L NaOH to 6.0, and then centrifuged at 2000 rpm for
10 min. We performed the hydroxyproline assay according
to instructions provided with a commercially available kit
(Nanjing Jiancheng Bioengineering Institute, China).
Sirius-Red Staining Analysis of Collagen I and
Collagen III. Lung sections were processed by sirius-red
staining for 1 min, following dewaxing and dehydration.
Polarized light microscopy was used to distinguish type I
and type III collagen fibers (Leica, Germany).
Immunohistochemical Analysis. Lung sections
were pretreated by 3% H
2
O
2
for 15 min, followed by the
appropriate antigen repairing treatment: digestion with
gastric enzyme for 30 min at 378C for collagen I and
collagen III; heating with microwave for 15 min at 998C for
tissue inhibitor of metalloproteinase 1 (TIMP-1), matrix
metalloproteinase-13 (MMP-13), and connective tissue
growth factor (CTGF). The slides were blocked with normal
bovine serum albumin (BSA) for 30 min at room temper-
ature. Collagen I or III (Boster Bioengineering Ltd., China),
MMP-13, TIMP-1 (Neomarkers, USA) and CTGF (Boster
Bioengineering Ltd., China) antibodies were then added at
378C for 2 h respectively in different experiment. We used
biotinylated anti-rabbit IgG and horseradish peroxidase
streptavidin (Santa Cruz, Canada) sequentially at 378C for
30 min. To develop a color product, diaminobenzidine
(DAB) was added for 1–10 min and Mayer’s hematoxylin
for 1 min. We observed labeling of the smooth muscle cells
in intrapulmonary arteries using light microscopy. The mean
percentage of intensity of antibody labeling (0%, ;50%,
and ;100%) was determined (9).
Statistical Analysis. All data are expressed as
means 6SD. We analyzed data using one-way analysis
of variance (ANOVA) followed by the Student-Newman-
Keuls tests for multiple comparisons. A value of P,0.05
was considered statistically significant.
H
2
S AND PULMONARY ARTERY COLLAGEN REMODELING 505
Results
Changes in Oxygen Saturation and H
2
S Con-
tent. In the present rat model of abdominal aorta-inferior
vena cava shunt, Qp/Qs in the shunt group and shuntþPPG
group increased significantly as compared with that of sham
and shamþPPG group (P ,0.01). The shunt and
shuntþPPG groups did not differ significantly (Fig. 1).
Compared with the sham group, the lung tissue H
2
S
content in the shunt group increased significantly (P ,
0.01). In the shuntþPPG group, lung tissue H
2
S content
decreased significantly (P ,0.01). The sham and
shamþPPG groups did not differ significantly in lung tissue
H
2
S content (Fig. 2).
RMT in Pulmonary Arteries. In contrast to the
sham group, RMT of intra-acinar pulmonary arteries in the
shunt group increased significantly (16.87 61.86% vs
12.67 61.26%, P,0.01). Compared with shunt group,
RMT of intra-acinar pulmonary arteries in the shuntþPPG
group increased significantly (23.54 63.07% vs 16.87 6
1.86%, P,0.01). RMT in sham and shamþPPG groups did
not differ significantly (12.67 61.26% vs 13.00 63.20%,
P.0.05) (Fig. 3).
Hydroxyproline Concentration and Collagen
Content of Lung Tissue. Hydroxyproline concentration
in lung tissue in the shunt group was significantly greater
than that of the sham group (P,0.01). In the shuntþPPG
group, hydroxyproline concentration was significantly
greater than that of the shunt group (P,0.01). There were
no significant differences between the sham and shamþPPG
groups (P.0.05) (Fig. 4).
Sirius-red staining showed that collagen I and collagen
III were more intensely stained in the pulmonary arteries of
the shunt group than in the sham group. The shuntþPPG
group showed more predominant collagen I and collagen III
than the shunt group (Fig. 5).
Pulmonary Artery Collagen I and Collagen
III. Collagen I and collagen III protein expressions of
intra-acinar pulmonary arteries in the shunt group were
significantly greater than the sham group (P,0.01). In the
shuntþPPG group, collagen I and collagen III protein
expressions of intra-acinar pulmonary arteries were signifi-
cantly greater than in the shunt group (P,0.01). There was
no significant difference in collagen I and collagen III
protein expressions of intra-acinar pulmonary arteries
between the sham and shamþPPG groups (P.0.05) (Figs.
6, 7). Using sirius-red staining, collagen I and collagen III in
rat pulmonary artery accumulation were also more obvious
Figure 1. Ratio of Qp/Qs in rats of different groups. #P,0.01 vs.
sham; *P,0.01 vs. shamþPPG.
Figure 2. Changes of lung tissue H
2
S content in rats of different
groups. #P,0.01 vs. sham; *P,0.01 vs. shunt.
Figure 3. RMT of pulmonary arteries in rats of different groups. #P,
0.01 vs. sham; *P,0.01 vs. shunt.
Figure 4. Changes of hydroxyproline concentration in lung tissue in
rats of different groups. #P,0.01 vs. sham; *P,0.01 vs. shunt.
506 LI ET AL
Figure 5. Sirius-red staining analysis of collagen I and collagen III in rat pulmonary artery under microscope (3200). A, sham, B, shamþPPG, C,
shunt, D, shuntþPPG. Sirius-red staining analysis of collagen I and collagen III in rat pulmonary artery under polarizing microscope (3200). E,
sham, F, shamþPPG, G, shunt, H, shuntþPPG.
H
2
S AND PULMONARY ARTERY COLLAGEN REMODELING 507
in the shunt group than in the sham group, and in the
shuntþPPG group versus the shunt group (Fig. 5).
MMP-13 and TIMP-1 in Pulmonary Arter-
ies.MMP-13 and TIMP-1 protein expressions of intra-
acinar pulmonary arteries as well as the ratio of MMP-13/
TIMP-1 in the shunt group were significantly greater than
the sham group (P,0.01). In the shuntþPPG group, MMP-
13 and TIMP-1 and the ratio of MMP-13/TIMP-1 were
significantly decreased relative to the shunt group (P,
0.01). The sham and shamþPPG groups did not differ
significantly (Fig. 6).
CTGF Protein Expression of Intra-Acinar Pul-
monary Arteries. In the shunt group, CTGF protein
expression of intra-acinar pulmonary arteries was signifi-
cantly greater than the sham group (P,0.01). In the
shuntþPPG group, CTGF was significantly greater than that
of the shunt group (P,0.01). There was no significant
difference in CTGF between the sham and shamþPPG
groups (P.0.05) (Figs. 6, 8).
Discussion
Pulmonary vascular structural remodeling and hyper-
tension due to high blood flow are common complications
of congenital heart disease observed with a left-to-right
shunt. However, the mechanisms responsible for the
remodeling induced by increased pulmonary blood flow
have been unclear. In the present study, we created a rat
model of high pulmonary blood flow by an abdominal aorta-
inferior vena cava shunting operation. We found that in the
shunt group, the ratio of pulmonary blood flow and systemic
blood flow (Qp/Qs) was significantly greater than in the
sham group, which suggests that pulmonary blood flow
increased as a result of the shunt. RMT, an indicator of
pulmonary vascular structural remodeling, was significantly
greater in the shunt group, which suggested that pulmonary
vascular structure remodeled due to high pulmonary blood
flow.
H
2
S is produced endogenously in mammalian tissues
from cystathionine metabolism mainly by 3 enzymes:
cystathionine-b-synthetase (CBS), cystathionine-c-lyase
(CSE), and 3-mercaptosulfurtransferase (MST) (10, 11).
The expression of these enzymes is tissue-specific, and CSE
mainly catalyzes H
2
S production in the cardiovascular
system. Our previous studies revealed that H
2
S plays an
important role in the pathophysiological process of some
cardio-pulmonary diseases such as spontaneous hyper-
tension (8), nitric oxide (NO) synthase inhibitor-induced
hypertension (12), hypoxia-induced pulmonary hyperten-
sion (13), septic and endotoxic shock (14), and isoproter-
enol-induced myocardial injury (15). These findings suggest
that endogenous H
2
S could be a novel gasotransmitter in the
cardiovascular system (16). In this study, we observed
markedly increased H
2
S production in a rat model of high
pulmonary blood flow.
To explore whether the CSE-H
2
S pathway contributes
to the pathogenesis of pulmonary vascular structural
remodeling induced by high pulmonary blood flow, we
applied D,L-propargylglycine (PPG), an irreversible inhib-
itor of CSE, in this experiment. CSE is a key enzyme in the
pathway of cystathionine metabolism to produce endoge-
nous H
2
S in rats. PPG was first reported by Abeles and
Walsh to inactivate rat liver cystathionase in 1973 (17).
After that, further studies showed that CSE enzyme is an
alpha 2 beta 2 tetramer where the subunits are distinguish-
able by charge but not by size and that each subunit of a
CSE tetramer became modified by PPG in an inactive CSE
(18, 19).
Although the accurate half life of PPG injected
intraperitoneally has not been reported, we found that the
content of PPG in serum reached its maximum at about 2 h
after intraperitoneal injection. Approximately 21.2% of
administered PPG was excreted into the urine within6hand
could not be detected in the urine by about 12 h after
administration (20). Moreover, we found that the activity of
CSE decreased to about 4% in rats 24 h after PPG injection
daily (21). Based on the above data and our previous study
(8), PPG was injected intraperitoneally once a day in this
experiment.
In the present study, we found that there was no
statistical difference in lung tissue H
2
S production between
sham and shamþPPG group as shown on Figure 2. As we
know, the basal endogenous lung tissue H
2
S production was
in a low level (17.35 61.76 lM) in sham group, because of
a low level of the activity of CSE at this state (22).
However, in shunt group, the endogenous lung tissue H
2
S
production was increased (37.56 62.13 lM). It is likely
that PPG plays a more obviously inhibitory role in
endogenous lung tissue H
2
S production in the shunt group
where the basal H
2
S level is relatively high compared with
the sham group, which has a low basal H
2
S level. Our study
found that in shunted animals administrated PPG for 4
weeks, the H
2
S content of lung tissue was significantly
lower than in those shunted rats without PPG treatment.
Figure 6. Changes in integral scores of collagen I, collagen III, MMP-
13, TIMP-1, and CTGF protein expressions in the pulmonary artery of
different groups. #P,0.01 vs. sham; *P,0.01 vs. shunt.
508 LI ET AL
Figure 7. Immunohistochemical analysis of collagen I protein expression in rat pulmonary artery of different groups (DAB, 3200). A, sham, B,
shamþPPG, C, shunt, D, shuntþPPG. Immunohistochemical analysis of collagen III protein expression in rat pulmonary artery of different
groups (DAB, 3200). E, sham, F, shamþPPG, G, shunt, H, shuntþPPG.
H
2
S AND PULMONARY ARTERY COLLAGEN REMODELING 509
However, the pulmonary vascular structure remodeled to an
even greater degree than in shunted animals without PPG,
which suggests that endogenous H
2
S possibly participates in
pulmonary vascular structural remodeling induced by high
pulmonary blood flow.
The present study aimed to explore the possible effect
of endogenous H
2
Soncollagenremodelingofthe
pulmonary artery in rats with high pulmonary blood flow.
Previous studies have shown that extracellular matrix
contributes a great deal to pulmonary vascular structural
remodeling. Collagen I and collagen III are the most
abundant components of the extracellular matrix of the
vascular wall. Changes in the absolute or relative contents of
collagen I and collagen III would likely result in structural
remodeling. Our previous studies showed that H
2
S reduced
the collagen remodeling of pulmonary artery under hypoxia
(23). However, it is unclear whether H
2
S exerts any
regulatory effect on the collagen accumulation in pulmonary
artery induced by high flow. Since collagen protein contains
hydroxyproline up to 10–14% by weight, hydroxyproline
concentration was measured as an index of collagen content
in this experiment (24). It was found that hydroxyproline
concentration of rat lung tissue and the expression of
collagen I and collagen III increased in the shunted animals.
Interestingly, these factors increased even more in the PPG
treated-shunt group where the production of endogenous
H
2
S was inhibited. This suggests that endogenous H
2
S
probably plays an important role in the regulation of
collagen remodeling induced by high pulmonary blood
flow.
Matrix metalloproteinases (MMPs; also called collage-
nases or matrixins) are key enzymes in extracellular matrix
degradation. MMPs involve a family of zinc-dependent
endopeptidases. Collagenase MMP-13 degrades mainly
fibrillar collagens, which include collagen I and collagen
III in the vascular wall. MMP activity is regulated at
different levels, including transcriptional control, extracel-
lular activation of proenzymes, and active enzyme, tissue
Figure 8. Immunohistochemical analysis of CTGF protein expression in rat pulmonary artery of different groups (DAB, 3200). A, sham. B,
shamþPPG, C, shunt, D, shuntþPPG.
510 LI ET AL
inhibitor of metalloproteinases (TIMPs). TIMPs bind to
active and alternative sites of the activated MMP to inhibit
the activity of MMP. The major member is TIMP-1, a 30-
kDa glycoprotein that is synthesized by most cells (25). It
was reported that an imbalance between gene expression of
interstitial collagenases and gene expression of TIMP-1
contributed to extracellular matrix accumulation (26).
Connective tissue growth factor (CTGF), a potent stimulator
of collagen synthesis (27), consists of 349 amino acids with
four distinct domains and induced by mechanical shear
stress in vitro (28, 29). As mentioned above, the balance of
MMP and TIMP-1 is involved in the regulation of collagen
degradation and CTGF contributed to collagen synthesis.
So, we included MMP, TIMP-1, CTGF as well as collagen
in the present study to investigate the role of H
2
S in the
regulation of pulmonary collagen accumulation.
In the present study, it was found that the expression of
MMP-13 and TIMP-1 is greater in the pulmonary artery
after 4 weeks of left-to-right shunt in rat. When PPG was
used to inhibit the production of endogenous H
2
S in shunted
animals, the expression of MMP-13 and TIMP-1 was
significantly down-regulated, which suggests that endoge-
nous H
2
S probably reduced collagen accumulation through
increasing its degradation in the shunted group. Our present
study indicated that CTGF expression up-regulated in
animals with 4 weeks of shunting. When PPG was used
to inhibit the production of endogenous H
2
S, CTGF up-
regulation was further increased. These results suggest that
endogenous H
2
S regulates the expression of CTGF, which
might be associated with the regulation of collagen
remodeling in pulmonary artery induced by high pulmonary
blood flow.
In conclusion, this study provides the first evidence that
endogenous H
2
S exerts regulatory effects on pulmonary
artery remodeling induced by high pulmonary blood flow.
Endogenous H
2
S might participate in regulating collagen
metabolism by affecting the degradation and synthesis of
collagen. However, the molecular mechanisms by which
H
2
S regulates pulmonary artery structural remodeling will
require further study.
1. Du J, Hui Y, Cheung Y, Bin G, Jiang H, Chen X, Tang C. The possible
role of hydrogen sulfide as a smooth muscle cell proliferation inhibitor
in rat cultured cells. Heart Vessels 19:75–80, 2004.
2. Pearson RJ, Wilson T, Wang R. Endogenous hydrogen sulfide and the
cardiovascular system-what’s the smell all about? Clin Invest Med 29:
146–150, 2006.
3. Wang R. The gasotransmitter role of hydrogen sulfide. Antioxid Redox
Signal 5:493–-501, 2003.
4. Xiaohui L, Junbao D, Lin S, Jian L, Xiuying T, Jianguang Q, Bing W,
Hongfang J, Chaoshu T. Down-regulation of endogenous hydrogen
sulfide pathway in pulmonary hypertension and pulmonary vascular
structural remodeling induced by high pulmonary blood flow in rats.
Circ J 69:1418–1424, 2005.
5. Zhao W, Zhang J, Lu Y, Wang R. The vasorelaxant effect of H(2)S as a
novel endogenous gaseous K(ATP) channel opener. EMBO J20:6008–
6016, 2001.
6. Garcia R, Diebold S. Simple, rapid, and effective method of producing
aortocaval shunts in the rat. Cardiovasc Res 24:430–432, 1990.
7. Ocampo C, Ingram P, Ilbawi M, Arcilla R, Gupta M. Revisiting the
surgical creation of volume load by aorto-caval shunt in rats. Mol Cell
Biochem 251:139–143, 2003.
8. Yan H, Du J, Tang C. The possible role of hydrogen sulfide on the
pathogenesis of spontaneous hypertension in rats. Biochem Biophys
Res Commun 313:22–27, 2004.
9. Barth PJ, Kimpel C, Roy S, Wagner U. An improved mathematical
approach for the assessment of the medial thickness of pulmonary
arteries. Pathol Res Pract 189:567–76, 1993.
10. Stipanuk MH, Beck PW. Characterization of the enzymic capacity for
cysteine desulphhydration in liver and kidney of the rat. Biochem J
206:267–277, 1982.
11. Erickson PF, Maxwell IH, Su LJ, Baumann M, Glode LM. Sequence of
cDNA for rat cystathionine gamma-lyase and comparison of deduced
amino acid sequence with related Escherichia coli enzymes. Biochem J
269:335–340, 1990.
12. Zhong G, Chen F, Cheng Y, Tang C, Du J. The role of hydrogen sulfide
generation in the pathogenesis of hypertension in rats induced by
inhibition of nitric oxide synthase. J Hypertens 21:1879–1885, 2003.
13. Chunyu Z, Junbao D, Dingfang B, Hui Y, Xiuying T, Chaoshu T. The
regulatory effect of hydrogen sulfide on hypoxic pulmonary hyper-
tension in rats. Biochem Biophys Res Commun 302:810–816, 2003.
14. Hui Y, Du J, Tang C, Bin G, Jiang H. Changes in arterial hydrogen
sulfide (H(2)S) content during septic shock and endotoxin shock in rats.
J Infect 47:155–160, 2003.
15. Geng B, Chang L, Pan C, Qi Y, Zhao J, Pang Y, Du J, Tang C.
Endogenous hydrogen sulfide regulation of myocardial injury induced
by isoproterenol. Biochem Biophys Res Commun 318:756–763, 2004.
16. Chen CQ, Xin H, Zhu YZ. Hydrogen sulfide: third gaseous transmitter,
but with great pharmacological potential. Acta Pharmacol Sin 28:1709–
1716, 2007.
17. Abeles RH, Walsh CT. Acetylenic enzyme inactivators. Inactivation of
gamma-cystathionase, in vitro and in vivo, by propargylglycine. J Am
Chem Soc 95: 6124–6125, 1973.
18. Marcotte P, Walsh C. Active site-directed inactivation of cystathionine
gamma-synthetase and glutamic pyruvic transaminase by propargyl-
glycine. Biochem Biophys Res Commun 62:677–682, 1975.
19. Johnston M, Jankowski D, Marcotte P, Tanaka H, Esaki N, Soda K,
Walsh C. Suicide inactivation of bacterial cystathionine gamma-
synthase and methionine gamma-lyase during processing of L-
propargylglycine. Biochemistry18:4690–4701, 1979.
20. Zhang J, Machida Y, Sugahara K, Kodama H. Determination of D,L-
propargylglycine and N-acetylpropargylglycine in urine and several
tissues of D,L-propargylglycine-treated rats using liquid chromatog-
raphy-mass spectrometry. J Chromatogr B Biomed Appl 660:375–379,
1994.
21. Kodama H, Mikasa H, Sasaki K, Awata S, Nakayama K. Unusual
metabolism of sulfur-containing amino acids in rats treated with DL-
propargylglycine. Arch Biochem Biophys 225:25–32, 1983.
22. Li XH, Bu DF, Jin HF, Ding YG, Du JB, Li J, Tang CS. The dynamic
changes in endogenous hydrogen sulfide pathway at the early stage of
pulmonary hypertension induced by high pulmonary flow in rats. Chin
J Appl Physiol 23:75–79, 2007.
23. Zhang CY, Du JB, Yan H, Tang CS. Effect of a new gasotransmitter,
hydrogen sulfide, on collagen remodeling of pulmonary artery under
hypoxia. Zhonghua Jie He He Hu Xi Za Zhi 28:448–452, 2005.
24. Edwards GA, Orien WD. Modified assay for determination of
hydroxyproline in a tissue hydrolyzate. Clin Chim Acta 104:161–
167, 1980.
25. Pe´rez-Ramos J, Lourdes Segura-Valdez M, Vanda B, Selman M, Pardo
A. Matrix metalloproteinases 2, 9, and 13, and tissue inhibitors of
H
2
S AND PULMONARY ARTERY COLLAGEN REMODELING 511
metalloproteinases 1 and 2 in experimental lung silicosis. Am J Respir
Crit Care Med 160:1274–1282,1999.
26. Ruiz V, Ordo´n˜ez RM, Berumen J, Ramı´rez R, Uhal B, Becerril C,
Pardo A, Selman M. Unbalanced collagenases/TIMP-1 expression and
epithelial apoptosis in experimental lung fibrosis. Am J Physiol Lung
Cell Mol Physiol 285:1026–1036, 2003.
27. Twigg SM, Joly AH, Chen MM, Tsubaki J, Kim HS, Hwa V, Oh Y,
Rosenfeld RG. Connective tissue growth factor/IGF-binding protein-
related protein-2 is a mediator in the induction of fibronectin by
advanced glycosylation end-products in human dermal fibroblasts.
Endocrinology 143:1260–1269, 2002.
28. Schild C, Trueb B. Mechanical stress is required for high-level
expression of connective tissue growth factor. Exp Cell Res 274:83–91,
2002.
29. Kessler D, Dethlefsen S, Haase I, Plomann M, Hirche F, Krieg T, Eckes
B. Fibroblasts in mechanically stressed collagen lattices assume a
‘‘synthetic’’ phenotype. J Biol Chem 276:36575–36585, 2001.
512 LI ET AL
