血小板源性生长因子影响血管弹性蛋白酶表达

探讨球囊损伤后血管平滑肌细胞丝氨酸弹性蛋白酶表达增加的机理。用球囊导管损伤Wistar系雄性大鼠主动脉或颈总动脉。以血小板源性生长因子A和大鼠胰腺丝氨酸弹性蛋白酶的地高辛标记RNA探针进行原位杂交，并用抗5-溴脱氧尿嘧啶抗体进行双重染色。用抗血小板源性生长因子从、抗血小板源性生长因子BB、抗胰腺弹性蛋白酶、抗人增殖细胞核抗原等抗体进行免疫染色或免疫双重染色。电镜观察细胞的超微结构。结果发现：①在球囊损伤后O．5～4h，血小板源性生长因子mRNA表达细胞多于弹性蛋白酶mRNA表达细胞；②增殖细胞和迁移细胞既有血小板源性生长因子mRNA和其蛋白表达，又有弹性蛋白酶mRNA和其蛋白表达；③迁移细胞多为增殖细胞核抗原染色阳性．细胞内可见到核分裂像。提示血小板源性生长因子可能是刺激中膜平滑肌细胞增殖、迁移并使其弹性蛋白酶增加的影响因子之一。     

弹性蛋白酶抑制剂对动脉损伤后血管平滑肌细胞增生作用的研究

目的　探讨弹性蛋白酶抑制对平滑肌细胞向内膜迁徙及增生的作用。方法　 2 0 0 2 - 0 8～ 2 0 0 3- 0 5 ,用 2F球囊导管损伤Wistar大鼠颈总动脉内皮 ,给弹力蛋白酶抑制剂 ,做损伤动脉组织染色及免疫染色 ,测定内膜及中膜的BrdU阳性细胞率、细胞数及面积。结果　球囊损伤后 ,弹力蛋白酶抑制剂给药 10d明显抑制内膜BrdU阳性细胞率、细胞数及面积 ,尽管给药 5d对上述指标无明显抑制作用。结论　弹性蛋白酶抑制剂通过降低内膜平滑肌增生抑制内膜肥厚 ,有可能成为用于治疗内膜增生的新药物。     

赖诺普利对自发性高血压大鼠血管平滑肌细胞离子泵活性及其mRNA表达的影响

目的 探讨赖诺普利对自发性高血压犬鼠动脉血管平滑肌细胞钠泵、钙泵活性及钠泵α1亚单位、钙泵亚型1mRNA表达水平的影响.方法 以自发性高血压大鼠动脉血管平滑肌细胞为研究对象,分为自发性高血压大鼠对照组、低剂量(1×10-6mol/L)赖诺普利组和高剂量(1×10-5mol/L)赖诺普利组,另以Wistar-Kyoto大鼠(WKY)为对照;分别用生化酶学方法和实时定量PCR检测细胞膜钠泵、钙泵活性和mRNA表达水平,用放射免疫分析法检测细胞培养液血管紧张素Ⅱ的含量.结果 与WKY对照组比较,自发性高血压大鼠动脉血管平滑肌细胞膜钠泵、钙泵活性及钠泵α1亚单位、钙泵亚型1mRNA表达水平均降低(P<0.01).赖诺普利能提高自发性高血压大鼠动脉血管平滑肌细胞膜钠泵、钙泵活性,并能上调钠泵α1亚单位和钙泵亚型1mRNA的表达水平(P<0.01).自发性高血压大鼠动脉血管平滑肌细胞培养液中血管紧张素Ⅱ含量高于WKY对照组(P<0.05),赖诺普利能降低其培养液中血管紧张素Ⅱ含量(P<0.05).结论 高血压大鼠动脉血管平滑肌细胞两种离子泵活性降低可能缘于它自身基因表达水平的下降,赖诺普利通过阻断血管紧张素Ⅱ而上调两种离子泵活性及基因表达.     

萘哌地尔衍生物YMⅢ对血管紧张素Ⅱ诱导大鼠胸主动脉平滑肌细胞增殖的抑制作用

目的 研究萘哌地尔衍生物YMⅢ对血管紧张素Ⅱ诱导Wistar大鼠和自发性高血压大鼠胸主动脉平滑肌细胞增殖的抑制作用及机制.方法 将Wistar大鼠和自发性高血压大鼠胸主动脉平滑肌细胞进行体外培养,采用四甲基偶氮唑盐比色法检测YMⅢ对胸主动脉平滑肌细胞和血管紧张素Ⅱ诱导胸主动脉平滑肌细胞增殖的影响;用实时逆转录聚合酶链反应技术检测血管紧张素原、c-myc mRNA表达.结果 未经血管紧张素Ⅱ处理的胸主动脉平滑肌细胞.0.1 μmol/L YMⅢ能抑制Wistar大鼠和自发性高血压大鼠胸主动脉平滑肌细胞增殖;YMⅢ(0.01、0.05、0.1 μmol/L)能呈浓度依赖性抑制血管紧张素Ⅱ所致Wistar大鼠和自发性高血压大鼠胸主动脉平滑肌细胞的增殖;YMⅢ(0.05～0.1 μmol/L)作用能使血管紧张素Ⅱ所致Wistar大鼠血管紧张素原、c-myc mRNA表达水平下调,而各浓度YMⅢ均能下调血管紧张素Ⅱ所致自发性高血压大鼠胸主动脉平滑肌细胞的血管紧张素原、c-myc mRNA表达.结论 YMⅢ明显抑制血管紧张素Ⅱ诱导大鼠胸主动脉平滑肌细胞的增殖,且抑制增殖作用在自发性高血压大鼠比在Wistar大鼠明显,其作用机制可能与下调血管紧张素原、c-myc mRNA的表达有关.     

p42/p44促分裂素原活化蛋白激酶上调炎症诱导的血管平滑肌细胞沉默调节蛋白1的表达

目的:研究炎症状态下血管平滑肌细胞中沉默调节蛋白1(SIRT1)的表达及其相关的信号通路。方法:以大鼠左颈总动脉球囊损伤和原代血管平滑肌细胞为模型,采用免疫组化的方法研究颈总动脉球囊损伤后SIRT1蛋白表达;采用免疫荧光观察血管平滑肌中TNF-α对SIRT1表达和定位的影响;采用Western blotting检测TNF-α对血管平滑肌细胞中SIRT1表达及p42/p44促分裂素原活化蛋白激酶(MAPK)表达的影响;并考察用MAPKs抑制剂处理后TNF-α对SIRT1表达的影响。结果:免疫组化结果显示球囊损伤的大鼠颈总动脉平滑肌细胞中SIRT1表达增加;免疫荧光显示SIRT1主要定位于血管平滑肌细胞核且TNF-α处理后SIRT1表达增加;Western blotting结果表明TNF-α处理的大鼠血管平滑肌细胞中SIRT1和磷酸化p42/p44 MAPK表达高于对照组;用p42/p44 MAPK抑制剂处理后,TNF-α诱导的SIRT1表达被抑制。结论:球囊损伤及TNF-α处理均可增高血管平滑肌细胞中SIRT1表达,p42/p44 MAPK信号通路参与对这一过程的调控。     

高血压家族史人脐动脉平滑肌细胞离子泵及自分泌血管紧张素Ⅱ和内皮素的变化

目的 比较高血压家族史和无高血压家族史的人脐动脉平滑肌细胞Na+,K+-ATPase,Ca2+-ATPase活性和亚单位mRNA表达的差异,比较两者人脐动脉平滑肌细胞培养上清液中血管紧张素Ⅱ和内皮素浓度的差异,探讨高血压家族史人脐动脉平滑肌细胞离子泵变化及其自分泌血管紧张素Ⅱ和内皮素的关系.方法 以FH+的人脐动脉平滑肌细胞为研究对象,以无高血压家族史的人脐动脉平滑肌细胞为对照,分别用生化酶学方法和逆转录聚合酶链反应技术检测两组细胞膜Na+,K+-ATPase,Ca2+-ATPase活性和质膜Na+,K+-ATPase 1-subunit mRNA、Ca2+-ATPase(plasma membrane Ca2+-ATPase,PMCA)亚型1(PMCA1)mRNA相对表达量;采用放射免疫法检测细胞培养上清液中血管紧张素Ⅱ和内皮素的含量.结果 高血压家族史组人脐动脉平滑肌细胞膜Na+,K+-ATPase,Ca2+-ATPase活性均高于无高血压家族史组(P<0.05),但两组hUASMC质膜Na+,K+-ATP泵α1-subunit mRNA表达和PMCA1 mRNA表达与无高血压家族史组无差异.高血压家族史组人脐动脉平滑肌细胞培养上清液中血管紧张素Ⅱ、内皮素浓度与无高血压家族史组无差异.结论 有高血压家族史者脐动脉平滑肌细胞膜Na+,K+-ATPase,Ca2+-ATPase活性增高并可能与其α1-Subunit、PMCA1 mRNA表达及自分泌血管紧张素Ⅱ和内皮素无明显关系.     

血管紧张素Ⅱ在高糖诱导大鼠系膜细胞MMP-9和TIMP-1 mRNA表达中的作用

高糖刺激大鼠系膜细胞血管紧张素Ⅱ（ATⅡ）的产生，高糖组和ATⅡ组系膜细胞基质金属蛋白酶9（MMP-9）mRNA表达降低，基质金属蛋白酶组织抑制物1（TIMP-1）mRNA表达增加，MMP-9／TIMP-1 mRNA比值下降，ATⅡ受体阻断剂Saralasin能逆转上述改变。     

血管紧张素Ⅱ对大鼠肾小球系膜细胞MMP-2和TIMP-2 mRNA表达的影响

正常大鼠肾小球系膜细胞的实验研究显示，血管紧张素Ⅱ（ATⅡ）对其质金属蛋白酶-2（MMP-2）的mRNA表达起降调节作用，对MMP-2基质金属蛋白酶组织抑制物-2（TIMP-2）的mRNA表达无明显影响。结果是，ATⅡ对MMP-2mRNA／TIMP-2mRNA二者表达的比值，起到降调节作用。     

血管紧张素Ⅱ对血管平滑肌细胞钙化的影响及信号通路

目的在钙化大鼠主动脉血管平滑肌细胞上观察血管紧张素Ⅱ对钙化的影响及其信号通道。方法用β磷酸甘油制备钙化的大鼠血管平滑肌细胞,再以血管紧张素Ⅱ,血管紧张素Ⅱ1型受体阻断剂缬沙坦,选择性蛋白激酶A或蛋白激酶C抑制剂等干预,通过Von Kossa染色及检测钙含量、碱性磷酸酶活性、骨钙素浓度和核心结合因子a1 mRNA表达来探讨血管紧张素Ⅱ对钙化的影响及其信号通道。结果血管紧张素Ⅱ增加钙化大鼠血管平滑肌细胞的钙含量、碱性磷酸酶活性、骨钙素浓度和核心结合因子a1 mRNA表达(P<0.05);而血管紧张素Ⅱ1型受体阻断剂和选择性蛋白激酶C抑制剂可阻断血管紧张素Ⅱ对血管平滑肌细胞的钙含量、碱性磷酸酶活性、骨钙素浓度和核心结合因子a1 mRNA表达的影响(P<0.05)。结论血管紧张素Ⅱ可促进β磷酸甘油诱导的血管平滑肌细胞钙化,其途径是通过血管紧张素Ⅱ1型受体,胞内信号途径是蛋白激酶C核心结合因子a1途径。     

血管紧张素Ⅱ2型受体基因可调控体外培养的血管平滑肌细胞基质金属蛋白酶2的表达

目的利用强力霉素—开放可调控哺乳动物表达系统,对体外培养血管平滑肌细胞的血管紧张素Ⅱ2型受体表达进行有效调控,在此基础上对基质金属蛋白酶2的表达受血管紧张素Ⅱ及其受体拮抗剂的影响进行研究。方法建立强力霉素可调控表达血管紧张素Ⅱ2型受体基因的双重稳定大鼠血管平滑肌细胞。观察该血管平滑肌细胞中血管紧张素Ⅱ2型受体受调控表达情况,以及血管紧张素Ⅱ及其1型、2型其受体拮抗剂干预上述细胞后基质金属蛋白酶2的表达情况变化。结果强力霉素—开放可调控哺乳动物表达系统可成功介导血管紧张素Ⅱ2型受体基因在原代培养大鼠主动脉血管平滑肌细胞的表达,该表达受到强力霉素给予/去除的紧密调控;强力霉素干预可在48h内迅速诱导该血管平滑肌细胞表达血管紧张素Ⅱ2型受体,该表达在强力霉素干预后72h进一步增强(P<0.01)。血管紧张素Ⅱ2型受体基因的可调控表达抑制由于血管紧张素Ⅱ干预后引起的基质金属蛋白酶2表达的增强(P<0.01)。这一作用被血管紧张素Ⅱ1型受体拮抗剂进一步增强(P<0.01);而被加入2型受体拮抗剂干预取消;同时给予上述两种拮抗剂时基质金属蛋白酶2的表达与基础状态时的情况一致。结论血管紧张素Ⅱ干预增强基质金属蛋白酶2的表达,该作用是通过血管紧张素Ⅱ1型受体介导的;经强力霉素诱导表达血管紧张素Ⅱ2型受体基因可以明显抑制这一生物学作用,说明血管紧张素Ⅱ2型受体基因经诱导后表达可以有效调控血管平滑肌细胞细胞外基质合成和降解。     

Heparin inhibits the expression of tissue-type plasminogen activator by smooth muscle cells in injured rat carotid artery.

Smooth muscle cells (SMCs) in balloon-injured rat carotid artery express tissue-type plasminogen activator (t-PA) at a time when they are migrating from the media to the intima. Since heparin inhibits SMC migration and intimal thickening, we have examined the possibility that heparin might also inhibit t-PA expression. Heparin (nonanticoagulant fraction; molecular weight, approximately 6,000) was administered by continuous intravenous infusion (1.0 mg/kg per hour) to Sprague-Dawley rats subjected to balloon injury of the left common carotid artery. At various times up to 14 days after injury, plasminogen activator expression was analyzed by zymography, plasmin generation, enzyme-linked immunosorbent assay, Northern blotting, and in situ hybridization. This dose of heparin inhibited SMC accumulation at 14 days by 60%. Both urokinase plasminogen activator (u-PA) and t-PA activity increased in injured arteries and reached a maximum at 7 days. Heparin treatment decreased t-PA, but not u-PA, activity. Total t-PA protein was decreased by treatment with heparin but not chondroitin sulfate, and the decrease in t-PA protein was associated with decreased t-PA mRNA in the media. These results in the injured rat carotid artery agree with our earlier observations that heparin inhibits t-PA gene expression in cultured baboon aortic SMCs. They also provide support for the hypothesis that heparin interferes with the expression of certain proteases required for SMC migration and proliferation.     

Soluble transforming growth factor-beta type II receptor inhibits negative remodeling, fibroblast transdifferentiation, and intimal lesion formation but not endothelial growth.

Using the rat balloon catheter denudation model, we examined the role of transforming growth factor-beta (TGF-beta) isoforms in vascular repair processes. By en face in situ hybridization, proliferating and quiescent smooth muscle cells in denuded vessels expressed high levels of mRNA for TGF-beta1, TGF-beta2, TGF-beta3, and lower levels of TGF-beta receptor II (TGF-betaRII) mRNA. Compared with normal endothelium, TGF-beta1 and TGF-beta2, as well as TGF-betaRII, mRNA were upregulated in endothelium at the wound edge. Injected recombinant soluble TGF-betaRII (TGF-betaR:Fc) localized preferentially to the adventitia and developing neointima in the injured carotid artery, causing a reduction in intimal lesion formation (up to 65%) and an increase in lumen area (up to 88%). The gain in lumen area was largely due to inhibition of negative remodeling, which coincided with reduced adventitial fibrosis and collagen deposition. Four days after injury, TGF-betaR:Fc treatment almost completely inhibited the induction of smooth muscle alpha-actin expression in adventitial cells. In the vessel wall, TGF-betaR:Fc caused a marked reduction in mRNA levels for collagens type I and III. TGF-betaR:Fc had no effect on endothelial proliferation as determined by reendothelialization of the denuded rat aorta. Together, these findings identify the TGF-beta isoforms as major factors mediating adventitial fibrosis and negative remodeling after vascular injury, a major cause of restenosis after angioplasty.     

Migration of adventitial myofibroblasts following vascular balloon injury: insights from in vivo gene transfer to rat carotid arteries

OBJECTIVES: Migration of adventitial fibroblasts, in addition to smooth muscle cell proliferation, plays a role in neointima formation following vascular injury. Previous studies have not directly addressed whether endogenous adventitial cells migrate towards the intima following balloon injury in the absence of medial dissection. We have employed an in vivo gene transfer technique to the rat carotid artery to directly label adventitial fibroblasts prior to balloon injury. METHODS: An adenoviral vector coordinating expression of nuclear targeted beta-galactosidase (AdLacZ) suspended in pluronic gel was applied to the perivascular surface of left carotid arteries of male Sprague-Dawley rats. Balloon catheter mediated vascular injury was performed on these arteries 4 days later and animals killed at 3, 7 and 14 days after injury. RESULTS: Expression of LacZ up to 14 days after application of the adenovirus was restricted only to the adventitia of uninjured arteries and absent from untransfected right carotid arteries. However, following balloon catheter injury, LacZ positive cells were observed within the medial layer of vessels by 3 days, and contributed to the population of cells within the neointima at 7-14 days. Adventitial cells in uninjured arteries did not express smooth muscle alpha-actin but after injury, LacZ positive cells migrating towards the lumen exhibited alpha-actin immunostaining, suggesting their change to a myofibroblastic phenotype. CONCLUSIONS: These findings provide direct evidence that adventitial fibroblasts migrate and contribute to neointima formation after balloon injury and show that in vivo gene transfer to the adventitia results in sustained transgene expression capable of labelling migrating adventitial cells within the media and neointima of injured vessels.     

Smooth muscle-specific SM22 protein is expressed in the adventitial cells of balloon-injured rabbit carotid artery.

During the "response-to-injury" process after a mechanical insult to the porcine coronary arteries, the adventitial cells acquire the structural characteristics of myofibroblasts before being incorporated into smooth muscle (SM) layer. We assessed whether the SM-specific SM22 protein can be used as a tracer of adventitial cell-myofibroblast differentiation in the mild balloon injury of rabbit carotid artery. To achieve this goal, we used 2 monoclonal anti-SM22 antibodies (E-11 and 1-B8) and a molecular probe for the SM22alpha mRNA isoform in immunocytochemical and in situ hybridization experiments. The differentiation profile and the migratory and proliferative ability of activated adventitial cells were evaluated by a panel of antibodies to some SM and nonmuscle antigens and pulse- and end-labeling with bromo-deoxyuridine, respectively. In adventitial cells, SM22 antigenicity and SM22alpha mRNA were detectable at days 2 and 4 and, to a lesser extent, at days 7 and 21 after injury, particularly near the adventitia-media interface and mostly colocalizing with bromo-deoxyuridine-positive cells. The pulse-labeling experiments showed that the large majority of these cells penetrated the outermost layer of the tunica media without migrating to the subendothelial region. The phenotypic features of activated migrating and nonmigrating adventitial cells resembled those of vimentin-actin myofibroblast subtype and fetal-type SM cells. These findings indicate that a direct exposure of adventitia to the lumen is not required for phenotypic changes and proliferation/migration of these cells. After comparison of the SM22 expression in arterial vessels during early stages of development, we hypothesize that in the injured carotid artery the mural incorporation of adventitial cells and the spatiotemporal activation of SM22 expression are reminiscent of the vascular morphogenetic process and suggest the existence of a stem cell-like reservoir in adventitia. The early adventitial upregulation of SM22 expression in the injured vessel might be related to a multistep transition process in which nonmuscle cells are converted to myofibroblasts and, possibly, to SM cells.     

同型半胱氨酸对球囊损伤大鼠颈动脉原癌基因表达的影响

目的:观察高蛋氨酸饮食诱导的高同型半胱氨酸(HCY)血症对大鼠颈动脉球囊损伤后血管组织原癌基因c-fos及c-jun的信使核糖核甙(mRNA)表达的影响,探讨其使血管成形术后新内膜过度增生的机制。方法:将12周龄健康雄性SD大鼠30只,随机分为对照组(普通饲料),10只,低蛋氨酸饮食组(1.2％蛋氨酸),10只,高蛋氨酸组(含2.0％蛋氨酸),10只,喂养4周后,以2F的球囊导管损伤左颈总动脉内皮的方法建立大鼠颈动脉球囊损伤模型,并以右颈总动脉作为对照(未行动脉球囊损伤),血管内皮损伤后1小时,处死动物,取颈总动脉,立即液氮冻存备用,采用RT-PCR方法检测血管组织c-fos及c-jun的mRNA表达情况,并做半定量分析。结果:低及高蛋氨酸组血浆HCY浓度明显高于饮食对照组(P<0.01),球囊损伤左颈总动脉各组组织的c-fos及c-jun mRNA表达均显著高于未损伤的右颈总动脉的(P<0.01),低蛋氨酸组和高蛋氨酸组c-fos及c-jun mRNA的表达均高于对照组的(P<0.01),高蛋氨酸组的c-fos及c-jun的mRNA表达明显高于低蛋氨酸组的(P<0.05)。结论:同型半胱氨酸能上调血管内皮损伤后动脉组织原癌基因c-fos及c-jun的mRNA的表达,且呈浓度依赖性,可能是其促进血管成形术后新内膜过度增生的机制之一。     

Nov gene encodes adhesion factor for vascular smooth muscle cells and is dynamically regulated in response to vascular injury

Nephroblastoma overexpressed (NOV) is a member of the CCN family (connective tissue growth factor, CYR61, and NOV) of proteins that are involved in regulating the proliferation, differentiation, and adhesion of a variety of cell types. We have examined the expression of the NOV: gene and NOV protein by vascular smooth muscle cells (VSMCs), in vitro and in vivo, and the effects of recombinant NOV on VSMCs. Rat aortic VSMCs were found to express NOV: mRNA and NOV protein in vitro and in vivo. NOV: expression in adult rat tissues was very high in the aorta and was detected only weakly in the brain and lung by Northern analysis (relative levels 33:3:1). During postnatal development (3 days to 12 weeks), the expression of NOV: was correlated with markers of the differentiated smooth muscle cell phenotype (smooth muscle myosin heavy chain and SM22 alpha). In the rat carotid artery balloon injury model, NOV: was detectable by in situ hybridization and was downregulated in the media of the injured artery compared with the uninjured artery at 7 and 14 days after injury. Expression in the developing intima was barely detectable at 7 days after injury except for strong expression at the luminal surface. At 14 days after injury, NOV: expression was substantially increased throughout the intima. In vitro studies of the function of NOV protein showed that it promoted VSMC adhesion via a mechanism that was divalent cation and Arg-Gly-Asp independent but that it did not modulate VSMC proliferation or phenotype. The strong expression and dynamic regulation of NOV: in the arterial wall, together with its ability to promote VSMC adhesion, suggest that it may be involved in homeostasis and repair.     

Angiotensin II induces smooth muscle cell proliferation in the normal and injured rat arterial wall

The present study was undertaken to explore the possibility that neointimal smooth muscle cells, the characteristic cells of restenosis and atherosclerosis, are selectively stimulated to replicate by a hypertensive stimulus. Angiotensin II (AII) was infused by osmotic minipumps for 2 weeks in 4.5-month-old rats. Group A received AII (200 ng/min) 2 weeks after a balloon catheter-induced injury of the thoracic aorta and left common carotid artery. Group B received only AII, group C only balloon denudation, and group D neither balloon injury nor AII. During the AII or Ringer's solution infusion, all animals received [3H]thymidine via a second minipump to measure DNA synthesis. AII increased the systolic pressure by more than 40 mm Hg. AII significantly increased DNA synthesis in the media of the carotid artery from 0.2 +/- 0.2% in group C to 2.5 +/- 1.5% in group A (mean +/- SD, n = 5 or 6). DNA synthesis in the neointima of the carotid artery significantly increased with AII from 4.8 +/- 4.2% in group C to 19.8 +/- 13.9% in group A. Cross-sectional area of the neointima almost doubled during AII infusion, and it increased approximately 25% in the media. Comparable results were obtained in the aorta. In a second experiment, AII was infused (125 ng/min) for 2 weeks in 11-week-old rats. Concomitantly, [3H]thymidine was given. Control rats received Ringer's solution and [3H]thymidine in their pumps. Blood pressures were elevated to the same extent as in the older animals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nitric oxide impacts endothelin-1 gene expression in intrapulmonary arteries of chronically hypoxic rats.

This study aimed to investigate whether nitric oxide (NO) could inhibit the elevated endothelin-1 (ET-1) gene expression by pulmonary artery endothelial cells or smooth muscle cells in chronically hypoxic rats by use of in situ hybridization. Male Wistar rats (n = 40) were randomly divided into 1-week hypoxia group, 1-week hypoxia with L-arginine (L-arg) group, 1-week hypoxia with N(omega)-nitro-L-arginine methyl ester (L-NAME) group, 2-week hypoxia group, 2-week hypoxia with L-arg group, and 2-week hypoxia with L-NAME group. All rats were put into a normobaric hypoxic chamber with an oxygen concentration of 10 +/- 0.5% for hypoxic challenge. The results showed that most pulmonary arteries had 1-50% of the endothelial cells showing positive signals for ET-1 expression in hypoxic rats, which was significantly suppressed by L-arg. L-NAME, however, significantly augmented ET-1 gene expression in pulmonary artery endothelial cells and smooth muscle cells. The results suggest that endogenous NO markedly inhibits ET-1 mRNA expression in both pulmonary artery endothelial cells and smooth muscle cells in chronically hypoxic rats, which may be one of the mechanisms by which NO modulates hypoxic pulmonary circulation.