Metallothionein inhibits homocysteine-induced proliferation of rat vascular smooth muscle cells

AIM:To investigate the effect of metallothionein(MT) on proliferation of rat vascular smooth muscle cells (VSMCs) stimulated by homocysteine and its mechanism. METHODS:VSMCs proliferation was measured by [³-H]-TdR incorporation, mitogen-activated protein kinase(MAPK)activity were determined by immunoprecipitation method, the intracellular contents of MT and malondialdehyde (MDA)were assayed by -hemoglobin saturation method and TBA reaction, respectively, and lactate dehydrogenase (LDH) leakage was measured by NADH oxidation. RESULTS:Hcy(10^-6-10^-4 mmol/L) stimulated [³-H]-TdR incorporation by the VSMCs in a concentration-dependent manner. Compared with control, [³-H]-TdR incorporation in VSMCs treated with 0.1 mmol/L Hcy was increased by 4.2 fold (P＜0.01). Meanwhile, Hcy enhanced MAPK activity, MDA formation and LDH release (P＜0.01)in a concentration-dependent manner. Treatment of VSMCs with MT alone did not change above parameters, compared with control. However, MT (10^-6-10^-4 mol/L)attenuated significantly Hcy-stimulated proliferation of VSMCs (P＜0.01)in a concentration-dependent manner. And MT inhibited obviously Hcy-induced activation of MAPK activity, MDA formation and LDH release. Preincubation of VSMCs with 0.5 mmol/L ZnCl₂ for 6 h induced an increase cellular MT content by 5.7-fold (P＜0.01). The MT-overexpressed VSMCs resisted Hcy-stimulating action on MAPK activity, MDA formation and LDH leakage (P＜0.01). CONCLUSION:These results show that MT has an inhibitory effect on Hcy-induced VSMCs proliferation, and that MT could inhibit Hcy-stimulated MAPK activity and lipid peroxidation.     

Fluvastatin inhibits migration of rat vascular smooth muscle cells

AIM: To investigate the inhibitory effects of fluvastatin on the migration of rat vascular smooth muscle cells (VSMCs) induced by angiotensin II (AngⅡ) and platelet derived growth factor-BB (PDGF-BB). METHODS: Cultured VSMCs derived from rat thoracic aorta were used. The activity of heat shock protein 27 (HSP27) was evaluated by Western blotting with specific phospho-HSP27 antibody. The effect of F-actin polymerization was detected by FITC-phalloidine staining and examined by confocal microscopy. Modified Boyden chamber technique was employed for VSMCs migration assessment. RESULTS: The phosphorylation of HSP27 in VSMCs was increased by the stimulation of AngⅡ and PDGF-BB in a concentration-dependent manner. Treatment with AngⅡ and PDGF-BB resulted in a substantial increase in the number of stress fibers and rearrangement of these structures into ordered parallel arrays. The migration of VSMCs was promoted by AngⅡ and PDGF-BB. Reorganization of actin cytoskeleton stimulated with AngⅡ and PDGF-BB was inhibited by a specific HSP27 inhibitor quercetin (100 μmol/L) pretreatment. The inhibitory rates of 100 μmol/L quercetin on the migration of VSMCs induced by AngⅡ and PDGF-BB were 55.3% and 53.6%,respectively (P<0.01). The phosphorylation of HSP27 in response to AngⅡ and PDGF-BB was suppressed by fluvastatin in a dose-dependent manner, and maximal inhibitory rates were between 42.1% and 58.5% with 10^-5 mol/L fluvastatin,respectively (P<0.01).CONCLUSION: Fluvastatin influences the migration of VSMCs in part by inhibiting HSP27 phosphorylation.     

Deoxyribozyme inhibits the proliferation of human umbilical artery smooth muscle cells

AIM: To observe the inhibition effects of 10-23 deoxyribozyme (DNAzyme) specific to human proliferating cell nuclear antigen (PCNA) gene on the proliferation of human umbilical artery smooth muscle cells (HUASMC) in vitro. METHODS: Using lipofectamine (Lip)-mediated method, the DNAzyme specific to PCNA was introduced into HUASMC. ［3H］-TdR incorporation was determined. The cell proliferation was examined by MTT assay and cell cycle was detected by flow cytometry. RESULTS: ［3H］-TdR incorporation in 1.0 μmol/L DNAzyme group was lower than that in control group (P<0.05) at 2 days after transfection. Compared with control group, the A value of MTT cholorimetric analysis decreased in 1.0 μmol/L DNAzyme group and antisense oligodeoxynucleotide (ASODN) group, at 2, 3 and 5 days after transfection significantly (P<0.01). The decrease in A value showed a dose-dependent manner within the experimental range at 5 days. After 2 days, the percentage of quiescence cells (G0/G1) was 73.8%, 54.7% and 41.1% in DNAzyme, ASODN and control groups, respectively. CONCLUSION: The DNAzyme specific to PCNA suppresses the proliferation of HUASMC effectively in vitro.     

PAF promotes proliferation of smooth muscle cells of rat airway

AIM: To study the effect of platelet-activating factor(PAF) on proliferation of cultured rat airway smooth muscle cells(ASMCs).METHODS: The cells were divided into control group and PAF group. The cells in PAF group were subdivided into four small groups by concentrations of PAF 10-6, 10-7, 10-8, 10-9 mol·L-1, MTT assay was used not only to investigate the effects of PAF on proliferation of ASMC but also to confirm the optimal concentration. Flow cytometry and immuneohistochemistry for proliferating cell nuclear antigen (PCNA) were also used to analyse its function on proliferation of ASMC.RESULTS: PAF (10-6-10-9mol·L-1) stimulated the cell proliferation and 10-7mol·L-1 PAF reached the maximal effect. The cell percentage of the ASMCs of 107 mol·L-1 PAF subgroup at G0/1 phase (68.67%) was much lower than that of control group (85.57%, P<0.01), in this subgroup, the percentage of expression of PCNA at 48 h (71.05%±1.22%) was significantly increased compared with the control group (53.27%±2.56%, P<0.05).CONCLUSION: PAF can stimulate the proliferation of cultured ASMC in a time-dependent, but not dose-dependent manner.     

Sodium Ferulate protects human aortic smooth muscle cells against oxidized Lipoprotein(a)

AIM: To investigate the influences of native and oxidized lipoprotein(a) on human arterial smooth muscle cell (SMC) proliferation, change of intracellular free calcium concentration ( [Ca²⁺]_i) and the protective effect of sodium ferulate(SF). METHODS: Lp(a) was oxidized by Cu²⁺ and the extent of oxidation was assessed by the MDA content.Human SMC were incubated in culture media with SF for 12 h, then exposed to Lp(a) and oxidized-Lp(a) , respectively. MTT colorimetry and flow cytometry were used to evaluated the proliferation of SMC and flurorescent indicator Fura-2/AM was used to determined [Ca²⁺]_i. RESULTS: ox-Lp(a) significantly promoted proliferation of SMC and increased [Ca²⁺]_i compared with Lp(a). SF(40,80 mg/L) remarkedly inhibited SMC proliferation and decreased the rising of [Ca²⁺]_i induced by ox-Lp(a) in a dose-dependent manner, but no effect on SMC proliferation and the increase in [Ca²⁺]_i induced by Lp(a).CONCLUSION: ox-Lp(a) induces the strong growth-promoting effect in SMC through increasing in [Ca²⁺]_i, which might be one of the cellular mechanisms responsible for the higher atherogenic potential of ox-Lp(a) compared with Lp(a), and this process can be prevented by inhibiting of oxidation by SF.     

XBP-01 accelerated apoptosis induced by oxidized low density lipoprotein in vascular smooth muscle cells

AIM: Previous studies performed with XBP-01 in vitro indicated that XBP-01 could inhibit vascular smooth muscle cells from being transformed into foam cell and could eliminate the atherosclerotic plaque in C57BL/6J mouse. This experiment is to investigate its mechanism of eliminating plaques in vitro. METHODS: The cultured porcine artery smooth muscle cells incubated with XBP-01 of 0.1 mg/L for 24 h after preincubated with oxidized low density lipoprotein of 15 mg/L for 72 h in vitro. The samples were analyzed by fluorescence microscope, confocal microscope system and flow cytometry. RESULTS: Apoptosis was triggered by being incubated with oxidized low density lipoprotein and this process was accelerated additionally by being incubated with XBP-01. CONCLUSION: XBP-01 can be effective in eliminating atherosclerotic plaque by accelerating the process in which oxidized low density lipoprotein induced smooth muscle cell apoptosis.     

Effects of FHL1 on proliferation and migration of rat pulmonary arterial smooth muscle cells stimulated by cigarette smoke

AIM:To explore the role of four-and-a-half LIM domain 1 (FHL1) in the proliferation and migration of rat distal pulmonary arterial smooth muscle cells (PASMCs) stimulated by cigarette smoke extract (CSE). METHODS:Rat distal PASMCs were isolated and primarily cultured. The cells were divided into 6 groups: blank control group, negative transfection group, FHL1 siRNA transfection group, CSE group, CSE + negative transfection group and CSE + FHL1 siRNA transfection group. The mRNA and protein expression of FHL1 was detected by real-time PCR and Western blotting, respectively. Cell proliferation and migration were determined by CCK-8 and Transwell assays, respectively. RESULTS:CSE promoted the proliferation and migration of PASMCs, and increased the expression of FHL1 protein (P<0.01), but did not change the expression of FHL1 mRNA (P>0.05). FHL1 siRNA transfection attenuated the proliferation and migration of PASMCs induced by CSE (P<0.01). CONCLUSION: FHL1 protein is involved in CSE-induced proliferation and migration of rat PASMCs.     

Native and oxidized low density and very low density lipoprotein enhance the expression of MIP-1α mRNA in aortic smooth muscle cells

AIM: To understand whether native and oxidized low density and very low density lipoprotein (n-LDL, n-VLDL, ox-LDL, ox-VLDL) enhance the expression of macrophage inflammatory protein (MIP)1α mRNA in cultured aortic smooth muscle cells (SMCs). METHODS: Native low density and very low density lipoprotein were isolated from normal blood donors by density gradient ultracentrifugation, and were oxidatively modified by adding CuCl2. After a 24 h-exposure of the cultured SMCs to n-LDL， n-VLDL， ox-LDL and ox-VLDL, respectively, the expression of MIP-1α mRNA was determined by in situ hybridization and RT-PCR. RESULTS: Cultured aortic SMCs expressed MIP-1α mRNA at low level. N-LDL， n-VLDL， ox-LDL and ox-VLDL enhanced the expression of MIP-1α mRNA in SMCs, ox-LDL and ox-VLDL showed stronger effect than n-LDL and n-VLDL, respectively. The effect of ox-VLDL was most striking. There was a significant difference between groups (P<0.01). CONCLUSION: N-LDL, n-VLDL, especially ox-LDL and ox-VLDL, may play an important role in the formation of early atherosclerotic lesion by inducing SMCs to express MIP-1α.     

Yangxue qingnao-containing serum inhibits rat vascular smooth muscle cell proliferation induced by lysophosphatidic acid

AIM: To observe the effects of Yangxue qingnao-containing serum on rat vascular smooth muscle cell (VSMC) proliferation induced by lysophosphatidic acid (LPA). METHODS: The [³H]-TdR incorporation and mitogen-activated protein kinasc (MAPK) activity were measured in cultured VSMC. End product of lipid peroxidation-MDA levels were also detected. RESULTS: 1×10^－9,1×10^－8 and 1×10^－7 mol/L LPA enhanced the cultured VSMC [³H]-TdR incorporation, increased MAPK activity and MDA content in a concentration-dependent manner. 5％, 10％ and 15％ Yangxue qingnao-containing serum concentration-dependently inhibited the increase in VSMC [³H]-TdR incorporation, MAPK activity and MDA content induced by LPA. CONCLUSIONS: LPA has a stimulating effect on VSMC proliferation. The LPA-induced intracellular signal transduction may be related to MAPK activity. Yangxue-qingnao can efficiently inhibit LPA -induced VSMC proliferation,MAPK activity and lipid peroxidation.     

Effects of probucol on the proliferation of rat vascular smooth muscle cells stimulated by basic fibroblast growth factor and hydrogen peroxide

AIM: To investigate the effect of probucol on proliferation of rat vascular smooth muscle cells(VSMC) stimulated by basic fibroblast growth factor (bFGF) and/or hydrogen peroxide(H₂O₂). METHODS: Effects of probucol on VSMC proliferation and DNA synthesis stimulated by bFGF and/or H₂O₂ were observed by means of MTT test, cell number count and [3H]-TdR incorporation. RESULTS: ①Probucol significantly inhibited proliferation and DNA synthesis in VSMC stimulated by bFGF and/or H₂O₂, with dosage-dependent manner. Cell number, A value and [3H]-TdR incorporation in group probucol+bFGF and group probucol+H₂O₂ were reduced by 40.0%, 39.1%, 45.5% and 46.9%, 45.0%, 39.5%, respectively, compared with group bFGF and group H₂O₂ (P＜0.05, P＜0.01, respectively). ②Pretreatment of VSMC with probucol for 24 h prior to bFGF and/or H₂O₂ stimulation exhibited significant inhibiton of VSMC proliferation and DNA synthesis, but after prestimulation by bFGF and/or H₂O₂ for 24 h, probucol had no influence on VSMC proliferation and DNA synthesis (P＞0.05). CONCLUSION: Probucol dramatically inhibited proliferation and DNA synthesis in VSMC stimulated by bFGF and/or H₂O₂, but had no inhibitory effect on the cell proliferation prestimulated by bFGF and /or H₂O₂.     

Effect of TRPC6 on PDGF-induced proliferation of rat airway smooth muscle cells

AIM:To investigate the role of canonical transient receptor potential channel 6 (TRPC6) in the proliferation of airway smooth muscle cells (ASMCs) induced by platelet-derived growth factor (PDGF). METHODS:Rat ASMCs were cultured by enzyme digestion and tissue adhesion. The method of indirect immunofluorescence was applied to identify the ASMCs and to detect the expression of TRPC6 in ASMCs. The proliferation of ASMCs was determined by CCK-8 assay. The mRNA expression of TRPC6 was tested by real-time PCR. The protein expression of TRPC6 was analyzed by Western blotting. The influence of TRPC6 blocker at different concentrations on the proliferation of ASMCs was measured by CCK-8 assay. RESULTS:The results of immunofluorescence indicated that TRPC6 expression in ASMCs was positive. PDGF at concentration of 20 μg/L induced the proliferation of ASMCs compared with control group (P<0.05). When ASMCs were treated with both PDGF and different concentrations of TRPC6 blocker SKF96365, the proliferation of ASMCs was attenuated in dose-dependent and time-dependent manners as compared with the cells treated with PDGF alone (P<0.05). The mRNA expression of TRPC6 in PDGF group was significantly increased (P<0.05) after ASMCs were treated with PDGF for 12 h, 24 h and 48 h. The protein level of TRPC6 in PDGF group was significantly increased after ASMCs were treated with PDGF for 24 h and 48 h compared with control group (P<0.05). CONCLUSION: Up-regulation of TRPC6 at mRNA and protein levels is most possibly related to the proliferation of ASMCs induced by PDGF. Therefore, TRPC6 is involved in the proliferation of ASMCs.     

Effect of nicotine on systolic and diastolic function of rat aortic smooth muscle cells

AIM:To observe the effects of nicotine on systolic and diastolic function of rat aortic vascular smooth muscle cells (VSMCs). METHODS:The primary rat aortic VSMCs were cultured in vitro. After exposed to nicotine at different concentrations for 24 h, the cytoskeleton of the VSMCs was stained with rhodamine-phalloidin,the photographs of the VSMCs in different experimental groups were taken and the surface area was measured to reflect the cell contractility. Collagen contraction method was also used to determine the effect of nicotine on the contractility of rat aortic VSMCs. RESULTS:The primary rat aortic VSMCs were successfully cultured. After the VSMCs were treated with nicotine (0.1 μmol/L, 1 μmol/L, 10 μmol/L and 100 μmol/L) for 24 h, the skeleton showed a significant contraction, and the cell plate shape was obviously enhanced in a concentration-dependent manner. The results showed that 10 μmol/L was the optimal concentration of nicotine for VSMCs (P<0.01). The collagen contraction method also showed that 10 μmol/L nicotine contracted the rat aortic VSMCs. With the increase in the nicotine action time, the maximum contraction effect was observed at 60 min (P<0.01). CONCLUSION:Nicotine has a strong contractile effect on VSMCs of rat aorta, and its contractile effect is dependent on concentration and time.     

Role of calcium-sensing receptor in hypoxia-induced proliferation of rat pulmonary artery smooth muscle cells

AIM: To explore the role of calcium-sensing receptor (CaSR) in rat pulmonary artery smooth muscle cells (PASMCs) and its effect on hypoxia-induced proliferation of PASMCs. METHODS: The expression and distribution of CaSRs were detected by Western blotting and immunofluorescence observation. The intracellular concentration of free calcium ([Ca]_i) was determined by confocal laser scanning microscopy. The cell viability was analyzed by MTT assay. The expression of PCNA and CaSRs was determined by Western blotting. RESULTS: CaSR protein was expressed in rat PASMCs. Hypoxia significantly increased the expression of CaSR and PCNA,[Ca]_i and the cell viability. GdCl₃ (an agonist of CaSR) or NPS2390 (an antagonist of CaSR) amplified or weakened the effect of hypoxia, respectively.CONCLUSION: CaSR is expressed in rat PASMCs. The activation of CaSR is involved in the proliferation of PASMCs induced by hypoxia.     

Role of receptors for oxidized low-density lipoprotein in pathogenesis of atherosclerosis

The formation of atherosclerosis （AS） is an evolutionary process. It undergoes lipid deposition, focal fibrosis in the intima of the arteries and atherosclerotic plaque formation, resulting in hardening of the vessel wall and stenosis of the lumen, which eventually leads to ischemic changes in the corresponding organs. In these processes, oxidized low-density lipoprotein （oxLDL）, an oxidative product of low-density lipoprotein, is considered to be a key trigger for AS development. In this paper, the role of the receptors for oxLDL in the development of AS is reviewed based on the recent studies.     

Origin of smooth muscle cells in vascular neointima from recipient bone marrow cells in rat aortic allograft

AIM: To study the expression of Sry gene in neointimal smooth muscle cells (NI-SMCs),and to investigate the origin of NI-SMCs in rat aortic allograft.METHODS: Sex-mismatched bone marrow transplantation was performed from male Wistar rat to female Wistar rat.Four weeks after transplantation,the aortic transplant model was constituted by means of micro-surgery in rat.The recipients were divided into four groups: female-female aortic isografts,female-female aortic allografts,male-male aortic allografts,female-chimera aortic allografts.Eight weeks after transplantation,aortic grafts were removed and processed for histological evaluation and immunohistochemistry assay.The Sry gene-specific PCR was performed on the genome of NI-SMCs to analyze its origin involved in aortic allograft.RESULTS: Excessive accumulation of α-SMA-positive SMCs resulted in significant neointima formation in rat aortic allografts.The neointimal area and NIA/MA ratio of transplanted artery were significantly increased in all aortic allograft groups compared with those in aortic isograft group (P<0.01).PCR assay indicated that a distinct DNA band with 225 bp emerged in the male-male aortic allograft group and chimera aortic allograft group respectively,but not in the female-female aortic allograft group,was observed.CONCLUSION: As the origin of NI-SMCs,recipient bone marrow cells contribute to the pathological neointimal hyperplasia of aortic allograft.     

Farrerol inhibits nicotine-induced proliferation of pulmonary vascular smooth muscle cells by enhancing Kv1.5 and Kv2.1 expression

AIM:To study the effect of farrerol (Far) on nicotine-induced proliferation of rat pulmonary smooth muscle cells (PASMCs), and further to explore its relationship with voltage-dependent potassium channels (Kv) 1.5 and Kv2.1. METHODS:Firstly, the effect of nicotine on the proliferation of PASMCs was detected by cell counting method, and the optimal concentration of nicotine was selected. Primary cultured PASMCs were randomly divided into 5 groups:normal control group, nicotine (1 μmol/L)group, nicotine (1 μmol/L) + Far (10^-6 mol/L, 10^-5 mol/L and 10^-4 mol/L) Far group. The activity of caspase-3 was measured by apoptosis kit, the cell viability was measured by CCK-8 assay, the apoptotic rate was analyzed by flow cytometry. The expression of Kv1.5 and Kv2.1, and apoptosis-related factors Bcl-2 and Bax at mRNA and protein levels was determined by RT-qPCR and Western blot respectively. RESULTS:Nicotine at 1 μmol/L increased the number of PASMCs to the maximum extent (P<0.01). Nicotine at 1 μmol/L significantly reduced the caspase-3 activity and enhanced the cell viability of the PASMCs (P<0.01). Farrerol at 10^-6~10^-4 mol/L eliminated the effect of PASMCs induced by nicotine in a concentration dependent manner. Compared with control group, nicotine at 1 μmol/L significantly increased the proliferation and inhibited the apoptotic rate of rat PASMCs (P<0.01). The apoptotic rate of PASMCs in farrerol intervention group was significantly higher than that in nicotine group (P<0.01). Nicotine at 1 μmol/L significantly inhibited the expression of Kv1.5, Kv2.1 and Bax but increased the expression of Bcl-2 in PASMCs (P<0.01). Farrerol at 10^-5 mol/L obviously inhibited the effect of PASMCs induced by nicotine. CONCLUSION:Farrerol eliminates nicotine-induced inhibition of caspase-3 and Bax, and enhancement of Bcl-2 in PASMCs by enhancing Kv1.5 and Kv2.1 expression.     

Effect of 27nt-miRNA on apoptosis of human umbilical vein endothelial cells induced by oxidized low-density lipoprotein

AIM To investigate the effect of 27nt-miRNA （27nt-miR） on apoptosis of human umbilical vein endothelial cells （HUVECs） induced by oxidized low-density lipoprotein （Ox-LDL） and its underlying mechanism. METHODS HUVECs were cultured in vitro and grouped as below： normal control group, Ox-LDL group, 27nt-miR+Ox-LDL group, anti-27nt-miR+Ox-LDL group and negative control+Ox-LDL group. The cells in Ox-LDL group were treated with Ox-LDL at 40 mg/L for 48 h, while those in normal control group were untreated but cultured normally. The cells in 27nt-miR+Ox-LDL group, anti-27nt-miR+Ox-LDL group and negative control+Ox-LDL group were transfected with their corresponding lentiviral vectors under the same procedure, followed by treatment with Ox-LDL at 40 mg/L for 48 h to induce apoptosis. The cell viability was measured by CCK-8 assay. The migration capacity was detected by scratch assay. The caspase-3 activity was measured by caspase-3 activity assay kit. The apoptotic rate was analyzed by Hoechst 33258 and flow cytometry. The mRNA and protein expression levels of Bcl-2, Bax and caspase-3 were determined by RT-qPCR and Western blot. RESUITS： Compared with negative control+Ox-LDL group, the cell viability and migration ability were significantly decreased by over-expression of 27nt-miR in the HUVECs （P<0.05）, while the activity of caspase-3 and apoptosis induced by Ox-LDL were significantly increased （P<0.05）. Furthermore, the mRNA and protein expression levels of Bax and caspase-3 were significantly up-regulated （P<0.05）, and the mRNA and protein expression level of Bcl-2 was down-regulated in 27nt-miR+Ox-LDL group （P<0.05）. Meanwhile, all the above indexes showed an opposite tendency in anti-27nt-miR+Ox-LDL group. CONCLUSION 27nt-miR promotes Ox-LDL-induced apoptosis and inhibits the viability and migration of HUVECs in vitro, possibly through regulating the expression of apoptotic/anti-apoptotic proteins such as Bax,caspase-3 and Bcl-2.     

Inhibitory effect of carbon monoxide on proliferation of rat pulmonary artery smooth muscle cells under anoxia

AIM: To investigate the effect of endogenous and exogenous carbon monoxide on the proliferation of pulmonary artery smooth muscle cells under anoxic condition. METHODS: Primary culture of rat PASMCs were passed every 3 days, the 3-5 passages were used. PASMCs were divided into 5 groups, cultured under normoxia and hypoxia and treated with HO inducer hemin, CO scavenger bovine hemoglobin (Hb) and exogenous carbon monoxide (CO), respectively. After 48 hours incubation under the conditions mentioned above, the following assay were carried out: 1) the MTT colorimetric assay and immunocytochemical staining were used to study the energy metabolism and the expression of proliferating cell nuclear antigen (PCNA) in PASMCs. 2) flow cytometry was used to analyze the cell cycle of PASMCs. RESULTS: In comparison with the control group, the value of MTT colorimetric assay was higher, the immunocytochemical staining of PCNA was stronger and the percentages of PASMCs in S and G₂M phases in the anoxia group were higher (P＜0.01). After treatment with hemin and CO, the above indexes were decreased (P＜0.01 or P＜0.05). But treatment with Hb made the above indexes increased (P＜0.01 or P＜0.05). CONCLUSION: The endogenous CO suppress the proliferation of PASMC in an autocrine way. Both the induction of endogenous CO by hemin and the treatment with exogenous CO could suppress the rat PASMCs' proliferation under anoxic condition.