缺氧对培养的肺动脉内皮细胞血管紧张素Ⅱ分泌的影响

缺氧是否通过影响血管内皮细胞的分泌功能而参与缺氧性肺动脉高压的发生尚不清楚。本实验动态观察了缺氧对培养的新生小牛内皮细胞（ＰＡＥＣ）的血管紧张素Ⅱ（ＡＴⅡ）分泌的影响。结果发现：２．５％Ｏ２缺氧早期（１．５ｈ）,ＰＡＥＣ的ＡＴⅡ分泌增加（Ｐ＜０．０１ｖｓ常氧组）,缺氧后期与常氧组无明显差别;０％Ｏ２缺氧早期（１．５－６ｈ）,ＡＴⅡ分泌明显降低（Ｐ＜０．０１ｖｓ常氧组及２．５％Ｏ２组）,后期ＡＴⅡ分泌明显增高（Ｐ＜０．０１ｖｓ常氧组及２．５％Ｏ２组）;无论缺氧还是常氧条件下,ＮＯ供体ＳＩＮ１显著抑制ＡＴⅡ的分泌（Ｐ＜０．０１）,而内源性ＮＯ抑制剂硝基精氨酸则明显促进ＡＴⅡ分泌（Ｐ＜０．０１）;０％Ｏ２缺氧２４ｈ后,ＰＡＥＣ细胞内ｃＧＭＰ含量明显降低（Ｐ＜０．０５）。上述结果表明缺氧可通过抑制ＰＡＥＣ的内源性ＮＯ产生而促进ＡＴⅡ的分泌,ＰＡＥＣ自分泌的改变可能参与缺氧性肺动脉高压的发生过程。     

ET—1,NO和缺氧对肺动脉平滑肌细胞钙内流及胶原合成的影响

肺血管平滑肌细胞是肺血管收缩反应的主要执行者,也是肺血管结构重建的重要参与者。本研究观察了内皮素－１（ＥＴ－１）一氧化氮（ＮＯ）和缺氧对培养的新生小牛肺动脉平滑肌细胞（ＰＡＳＭＣ）钙内流以及胶原合成的影响,结果表明ＥＴ－１和缺氧可促进ＰＡＳＭＣ的钙内流;ＮＯ供应剂硝普钠（ＳＭＰ）可抑制ＥＴ－１诱导的钙内流,其作用呈剂量依赖性,ＳＮＰ还可以剂量依赖地抑制了ＰＡＳＭＣ的胶原合成,而缺氧可促进ＰＡＳＭＣ     

低氧、血管紧张素Ⅱ对肺内小动脉平滑肌细胞膜Ca2 ┐ATPase活力的影响

本课题观察了低氧及血管紧张素Ⅱ（ａｎｇｉｏｔｅｎｓｉｎⅡ,ＡｎｇⅡ）对分离培养家兔肺内小动脉平滑肌细胞（ＰＡＳＭ－Ｃｓ）膜Ｃａ２＋－ＡＴＰａｓｅ活力的影响,同时用钙通道阻断剂维拉帕米（ｖｅｒａｐａｍｉｌ,ＶＰ）进行干预,进一步了解细胞内钙与Ｃａ２＋－ＡＴＰａｓｅ活力的关系。结果表明：ＰＡＳＭＣｓ膜Ｃａ２＋－ＡＴＰａｓｅ活力对低氧具有短暂的耐受性,随低氧时间延长,Ｃａ２＋－ＡＴＰａｓｅ活力呈时间依赖性抑制;低氧、ＡＮＧⅡ均能抑制Ｃａ２＋－ＡＴＰａｓｅ活力（Ｐ＜０．０１）低氧＋ＡⅡ对Ｃａ２＋－ＡＴＰａｓｅ活力的抑制具叠加效应（Ｐ＜０．０５）;ＶＰ可逆转低氧、ＡｎｇⅡ、低氧＋ＡｎｇⅡ对Ｃａ２＋－ＡＴＰａｓｅ活力的抑制（Ｐ＜０．０１）。结果提示：低氧,ＡＮＧⅡ可通过抑制肺血管平滑肌细胞膜Ｃａ２＋－ＡＴＰａｓｅ活力而可能削弱肺血管平滑肌舒张功能也可能是低氧性肺动脉高压（ＨＰＨ）形成的原因之一。     

ET－1，NO和缺氧对肺动脉平滑肌细胞钙内流及胶原合成的影响

肺血管平滑肌细胞是肺血管收缩反应的主要执行者,也是肺血管结构重建的重要参与者。本研究观察了内皮素１（ＥＴ１）,一氧化氮（ＮＯ）和缺氧对培养的新生小牛肺动肺平滑肌细胞（ＰＡＳＭＣ）钙内流以及胶原合成的影响。结果表明ＥＴ１和缺氧可促进ＰＡＳＭＣ的钙内流,ＮＯ供应剂硝普钠（ＳＭＰ）可抑制ＥＴＩ诱导的钙内流,其作用呈剂量依赖性,ＳＮＰ还可以剂量依赖地抑制ＰＡＳＭＣ的胶原合成,而缺氧可促进ＰＡＳＭＣ的胶原合成。     

三种钠尿肽抑制大鼠肺动脉平滑肌细胞增殖效应的比较

本文比较了心房钠尿肽（ＡＮＰ）、Ｃ－型钠尿肽（ＣＮＰ）、血管钠肽（ＶＮＰ）抑制肺动脉平滑肌细胞（ＰＡＳＭＣｓ）增殖的效应。用蛋白激酶Ｃ激动剂佛波酯（ＰＭＡ）刺激体外培养大鼠ＰＡＳＭＣｓ的增殖,以总蛋白含量和ＭＴＴ比色ＯＤ值为指标,观察三种钠尿肽对ＰＭＡ刺激大鼠ＰＡＳＭＣｓ增殖的影响。结果表明,ＰＭＡ（１０＾－９－１０＾－７ｍｏｌ／Ｌ）显著升高（Ｐ＜０．０５）ＰＡＳＭＣｓ的总蛋白含量和ＭＴＴＯＤ值,     

慢性肺心病肺动脉平滑肌细胞的胶原合成：体内及体外观察

肺动脉构形重建（ｓｔｒｕｃｔｒｕｒａｌｒｅｍｏｄｅｌｉｎｇ）是慢性肺心病的重要血管病变,但其发生机制至今未完全明了。病变以血管中膜平滑肌细胞肥大、增生和细胞外基质（包括纤维性与非纤维性成分）增多导致的血管壁增厚、血管腔狭窄为特征。本文用天狼星红－偏振光显微镜观察,真彩色全自动图像分析法,测量１０例慢性肺心病尸检肺小动脉中膜厚度及中膜内Ⅰ、Ⅲ两型胶原的含量和所占的百分比。用３Ｈ－胸腺嘧院核苷和３Ｈ－脯氨酸掺入法,观察缺氧内皮细胞条件培养液（ＨＥＣＣＭ）对培养的肺动脉平滑肌细胞（ＰＡＳＭＣＳ）ＤＮＡ及胶原合成的影响。结果：（１）肺心病组４３７支肌型肺动脉平均中膜厚占血管直径的百分值高于对照组５±１．０８％;（２）肺心病组的Ⅰ型和Ⅲ型胶原面积分别占中膜面积的５４．６２％和５１９％,而对照组两型胶原占中膜面积小于２％。（３）ＨＥＣＣＭ组平滑肌细胞的３Ｈ－ＴｄＲ和３Ｈ－脯氨酸掺入量（ｃｐｍ值）,均明显高于常氧对照组（ＮＥＣＣＭ）,两组相比,有显著性差异（Ｐ＜０．０１）。（４）细胞周期分析,ＨＥＣＣＭ组平滑肌细胞的Ｇ０／Ｇ１期细胞数百分值比ＮＥＣＣＭ组少２８％,Ｇ２＋Ｍ期细胞百分值则比ＮＥＣＣＭ组高３０％。可以认为,缺     

脂多糖对离体培养大鼠血管平滑肌细胞增殖的影响

本研究观察到１０－７～１０－５ｋｇ／Ｌ脂多糖（ｌｉｐｏｐｏｌｙｓａｃｈａｒｉｄｅ,ＬＰＳ）可显著促进血管平滑肌细胞（ＶＳＭＣ）的增殖及ＤＮＡ的合成（Ｐ＜００５）。５×１０－４～１０－３ｋｇ／ＬＬＰＳ却抑制ＶＳＭＣ的增殖及ＤＮＡ的合成,降低其活力（Ｐ＜００１）,并呈时间依赖效应。一氧化氮合酶抑制剂ＮＮｉｔｒｏＬＡｒｇｉｎｉｎｅ（ＬＮＮＡ）可拮抗ＬＰＳ的抑制作用。大剂量ＬＰＳ作用组ＶＳＭＣ上清液中一氧化氮（ＮＯ）代谢产物ＮＯ－３和ＮＯ－２的含量与对照组相比显著增加（Ｐ＜００１）,４８ｈ组比２４ｈ组增加９１％,７２ｈ组比４８ｈ组增加４５％;同时,诱导性一氧化氮合酶（ｉｎｄｕｃｔｉｖｅｎｉｔｒｉｃｏｘｉｄｅｓｙｎｔｈａｓｅ,ｉＮＯＳ）免疫组化染色呈阳性。结果表明,低浓度ＬＰＳ促进ＶＳＭＣ增殖和ＤＮＡ合成,而高浓度ＬＰＳ却明显抑制ＶＳＭＣ增殖和ＤＮＡ合成,降低其活力。这种抑制作用可能与ＬＰＳ诱导ＶＳＭＣ产生的ＮＯ有关。     

血管平滑肌细胞增殖与Cdk抑制蛋白p27的表达

ｐ２７蛋白是细胞周期素依赖性激酶（Ｃｄｋ）抑制蛋白家族中的一种,主要对外部促进或抑制细胞增殖的信号起反应。本研究应用流式细胞仪（ＦＣＭ）双标记的方法观察血管紧张素Ⅱ（ＡｎｇⅡ）、血管加压素（ＡＶＰ）和血小板源生长因子（ＰＤＧＦ）对血管平滑肌细胞（ＶＳＭＣｓ）细胞周期百分比和ｐ２７蛋白表达量的影响。静止状态培养的ＶＳＭＣｓ加入ＡｎｇⅡ,ＡＶＰ,ＰＤＧＦＢＢ后,在不同时间收集细胞,用碘化丙啶（ＰＩ）标记细胞ＤＮＡ,以确定细胞所处的周期。用ｐ２７蛋白的单抗和标记了ＦＩＴＣ的二抗标记细胞,通过流式细胞仪测定被激发出的荧光量来确定细胞ｐ２７蛋白表达的相对量。结果显示,ＡｎｇⅡ刺激ＶＳＭＣｓ增生,其蛋白含量增加了４３６％（Ｐ＜００１）,但不抑制ｐ２７蛋白的表达;ＡＶＰ可轻度抑制ｐ２７的表达,有轻度促进ＶＳＭＣｓ增殖和增生的作用（Ｐ＜００５）;ＰＤＧＦ明显抑制ｐ２７的表达,引起细胞增殖。本研究结果提示,ｐ２７蛋白抑制ＶＳＭＣｓ通过Ｇ１期进入Ｓ期,是抑制ＶＳＭＣｓ增殖的重要调节因子。     

5—羟色胺对肺动脉平滑肌细胞在缺氧条件下增殖的作用

本研究应用细胞培养、＾３Ｈ－ＴｄＲ掺入,核酸分子杂交、免疫组织化学染色技术,探讨无氧（０％Ｏ２＋９５％Ｎ２＋５％ＣＯ２）和／或低氧（２．５￣３％Ｏ２＋９２％Ｎ２＋５％ＣＯ２）对新生小牛肺动脉平滑肌细胞增殖和５－羟色胺转载体基因表达的影响。结果表明：无氧２４ｈ可刺激ＰＡＳＭ的ＤＮＡ合成,＾３Ｈ－ＴｄＲ的掺入增加（Ｐ〈０．０５）,加入５－羟色胺能非常显著地促进无氧ＰＡＳＭ增殖（Ｐ〈０．００１）,而对常     

内皮素－1对缺氧肺动脉平滑肌细胞的增殖作用

内皮素（ＥＴ）是至今所发现的最强的内源性血管收缩肽,近年来发现ＥＴ－１能促进血管平滑肌细胞增殖。本研究表明ＥＴ－１对缺氧培养的肺动脉平滑肌细胞（ＰＡＳＭＣ）有剂量依赖的增殖作用,缺氧可促进ＰＡＳＭＣ的ＤＮＡ合成且增加ＥＴ－１的丝裂原作用。ＥＴ－１的丝裂原作用主要由其Ａ型受体（ＥＴＲ＿Ａ）所介导,ＥＴＲ＿Ａ的特异拮抗剂ＢＱ１２３可显著抑制缺氧以及缺氧与ＥＴ－１协同所产生的增殖作用,而且发现ＥＴＲ＿Ａ在缺氧培养的ＰＡＳＭＣ中的表达显著高于常氧对照组ＰＡＳＭＣ。本研究表明ＥＴ－１参与了缺氧性肺动脉结构重组,而缺氧可增强ＰＡＳＭＣ对ＥＴ－１的增殖反应性。     

缺氧时肺动脉内皮细胞与肺动脉平滑肌细胞增殖的相互影响

血管内皮细胞和血管平滑细胞在结构和功能上关系密切,两者的相互在与血管舒缩笔血和壁结构。本文观察了培养的小牛肺动脉内皮细胞（ＰＡＥＣｓ）和肺动平滑肌细胞（ＰＡＳＭＣＳ）缺氧时在细胞增殖方面的相互影响。ＰＡＳＭＣＳ常氧条件培养基（ＣＭ）可使ＰＡＥＣＳ的＾３Ｈ－ＴｄＲ掺入降低约５８％,缺氧ＣＭ对ＰＡＥＣＳ的＾３Ｈ－ＴｄＲ掺入无明显的抑制作用;ＰＡＥＣＳ的常氧ＣＭ使ＰＡＳＭＳ的＾３Ｈ－ＴｄＲ掺入升高约６０     

N-acetylcysteine inhibits hypoxic pulmonary hypertension most effectively in the initial phase of chronic hypoxia

Exposure to chronic hypoxia results in hypoxic pulmonary hypertension (HPH). In rats HPH develops during the first two weeks of exposure to hypoxia, then it stabilizes and does not increase in severity. We hypothesize that free radical injury to pulmonary vascular wall is an important mechanism in the early days of the hypoxic exposure. Thus antioxidant treatment just before and at the beginning of hypoxia should be more effective in reducing HPH than antioxidant therapy of developed pulmonary hypertension. We studied adult male rats exposed for 4 weeks to isobaric hypoxia (F(iO2) = 0.1) and treated with the antioxidant, N-acetylcysteine (NAC, 20 g/l in drinking water). NAC was given "early" (7 days before and the first 7 days of hypoxia) or "late" (last two weeks of hypoxic exposure). These experimental groups were compared with normoxic controls and untreated hypoxic rats (3-4 weeks hypoxia). All animals kept in hypoxia had significantly higher mean pulmonary arterial blood pressure (PAP) than normoxic animals. PAP was significantly lower in hypoxic animals with early (27.1 +/- 0.9 mmHg) than late NAC treatment (30.5 +/- 1.0 mmHg, P < 0.05; hypoxic without NAC 32.6 +/- 1.2 mmHg, normoxic controls 14.9 +/- 0.7 mmHg). Early but not late NAC treatment inhibited hypoxia-induced increase in right ventricle weight and muscularization of distal pulmonary arteries assessed by quantitative histology. We conclude that release of free oxygen radicals in early phases of exposure to hypoxia induces injury to pulmonary vessels that contributes to their structural remodeling and development of HPH.     

A Critical Role of the mTOR/eIF2α Pathway in Hypoxia-Induced Pulmonary Hypertension

Enhanced proliferation of pulmonary arterial vascular smooth muscle cells (PASMCs) is a key pathological component of vascular remodeling in hypoxia-induced pulmonary hypertension (HPH). Mammalian targeting of rapamycin (mTOR) signaling has been shown to play a role in protein translation and participate in the progression of pulmonary hypertension. Eukaryotic translation initiation factor-2α (eIF2α) is a key factor in regulation of cell growth and cell cycle, but its role in mTOR signaling and PASMCs proliferation remains unknown. Pulmonary hypertension (PH) rat model was established by hypoxia. Rapamycin was used to treat rats as an mTOR inhibitor. Proliferation of primarily cultured rat PASMCs was induced by hypoxia, rapamycin and siRNA of mTOR and eIF2α were used in loss-of-function studies. The expression and activation of eIF2α, mTOR and c-myc were analyzed. Results showed that mTOR/eIF2α signaling was significantly activated in pulmonary arteries from hypoxia exposed rats and PASMCs cultured under hypoxia condition. Treatment with mTOR inhibitor for 21 days attenuated vascular remodeling, suppressed mTOR and eIF2α activation, inhibited c-myc expression in HPH rats. In hypoxia-induced PASMCs, rapamycin and knockdown of mTOR and eIF2α by siRNA significantly abolished proliferation and increased c-myc expression. These results suggest a critical role of the mTOR/eIF2αpathway in hypoxic vascular remodeling and PASMCs proliferation of HPH.     

Grape seed procyanidin extract attenuates hypoxic pulmonary hypertension by inhibiting oxidative stress and pulmonary arterial smooth muscle cells proliferation

Hypoxia-induced oxidative stress and excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) play important roles in the pathological process of hypoxic pulmonary hypertension (HPH). Grape seed procyanidin extract (GSPE) possesses antioxidant properties and has beneficial effects on the cardiovascular system. However, the effect of GSPE on HPH remains unclear. In this study, adult Sprague–Dawley rats were exposed to intermittent chronic hypoxia for 4 weeks to mimic a severe HPH condition. Hemodynamic and pulmonary pathomorphology data showed that chronic hypoxia significantly increased right ventricular systolic pressures (RVSP), weight of the right ventricle/left ventricle plus septum (RV/LV+S) ratio and median width of pulmonary arteries. GSPE attenuated the elevation of RVSP, RV/LV+S, and reduced the pulmonary vascular structure remodeling. GSPE also increased the levels of SOD and reduced the levels of MDA in hypoxia-induced HPH model. In addition, GSPE suppressed Nox4 mRNA levels, ROS production and PASMCs proliferation. Meanwhile, increased expression of phospho-STAT3, cyclin D1, cyclin D3 and Ki67 in PASMCs caused by hypoxia was down-regulated by GSPE. These results suggested that GSPE might potentially prevent HPH via antioxidant and antiproliferative mechanisms.     

尾加压素对常氧及低氧大鼠肺动脉平滑肌细胞周期的影响

目的：观察新近发现的缩血管活性肽人类尾加压素Ⅱ（human urotensin Ⅱ,hUII)对体外培养的大鼠肺动脉平滑肌细胞（PASMCs)周期的影响。方法：体外培养大鼠肺动脉平滑肌细胞,加入不同浓度（mol/L)的hUII(10^-7,10^-8,10^-9),在常氧及低氧条件下孵育12h,用流式细胞术碘化丙啶染色法,分析PASMCs DNA直方图细胞周期时项、细胞增殖指数及凋亡亚二倍体峰的改变,以初步观察hUII对PASMCs增殖与凋亡的影响。结果：hUII呈浓度依赖方式促进PASMCs的增殖,主要表现为细胞周期S期的百分比增加,细胞增殖指数（PI）增高,常氧作用比低氧作用更明显。hUII浓度（mol/L)为10^-7,10^-8,10^-9时,与PASMCs常氧作用12h,PI分别比对照组增加了的175％、135％、118％;低氧作用12h,PASMCs PI分别是对照组的135％、118％、103％,hUII浓度为10^-7mol/L时作用最明显。同时DNA直方图分析各浓度范围的hUII均未见PASMCs凋亡亚二倍体峰出现。结论：hUII以剂量依赖方式刺激常氧及低氧PASMCs S期DNA合成速率,使PI增高,提示hUII具有明显的促PASMCs增殖作用。     

Effect of normoxia and hypoxia on K(+) current and resting membrane potential of fetal rabbit pulmonary artery smooth muscle

At birth, the increase in O(2) tension (pO(2)) is an important cause of the decrease in pulmonary vascular resistance. In adult animals there are impressive interspecies differences in the level of hypoxia required to elicit a pulmonary vasoconstrictor response and in the amplitude of the response. Hypoxic inhibition of some potassium (K(+)) channels in the membrane of pulmonary arterial smooth muscle cells (PASMCs) helps to initiate hypoxic pulmonary vasoconstriction. To determine the effect of the change in pO(2) on fetal rabbit PASMCs and to investigate possible species-dependent differences, we measured the current-voltage relationship and the resting membrane potential, in PASMCs from fetal resistance arteries using the amphotericin-perforated patch-clamp technique under hypoxic and normoxic conditions. Under hypoxic conditions, the K(+) current in PASMCs was small, and could be inhibited by 4-aminopyridine, iberiotoxin and glibenclamide, reflecting contributions by Kv, K(Ca) and K(ATP) channels. The average resting membrane potential was -44.3+/-1.3 mV (n=29) and could be depolarized by 4-AP (5 mM) and ITX (100 nM) but not by glibenclamide (10 microM). Changing from hypoxia, that mimicked fetal life, to normoxia dramatically increased the K(Ca) and consequently hyperpolarized (-9.3+/-1.7 mV; n=8) fetal rabbit PASMCs. Under normoxic conditions K(+) current was reduced by 4-AP with a significant change in resting membrane potential (11.1+/-1.7 mV; n=8). We conclude that resting membrane potential in fetal rabbit PASMCs under both hypoxic and normoxic conditions depends on both Kv and K(Ca) channels, in contrast to fetal lamb or porcine PASMCs. Potential species differences in the K(+) channels that control resting membrane potential must be taken into consideration in the interpretation of studies of neonatal pulmonary vascular reactivity to changes in O(2) tension.     

慢性间歇性低氧降低急性缺氧对大鼠肺动脉平滑肌细胞膜上电压门控性钾通道的抑制

为了从离子通道水平上探讨机体低氧适应的离子机制,本实验将雄性 SD 大鼠随机分为常氧对照组和慢性间歇性低氧组[氧浓度(10 ± 0.5) %, 间断缺氧每天 8 h]。用酶解法急性分离单个大鼠肺内动脉平滑肌细胞(pulmonary artery smoothmuscle cells, PASMCs),以全细胞膜片钳技术记录 PASMCs 膜上的电压门控性钾通道 (voltage-gated potassium channel, KV) 电流,观察急性缺氧对慢性间歇性低氧大鼠 PASMCs 的 KV 的影响, 为机体适应低氧能力提供实验依据。结果显示:⑴常氧对照组在电流钳下,急性缺氧可使膜电位明显去极化(由-47.2 ±2.6 mV 去极到 -26.7 ±1.2 mV ); 在电压钳下, 急性缺氧可显著抑制 KV电流( 60 mV 时, KV电流密度从 153.4 ± 9.5 pA/pF降到 70.1 ± 10.6 pA/pF), 峰电流的抑制率为(57.6 ± 3.3) %, 电流-电压关系曲线向右下移。⑵慢性间歇性低氧组KV电流密度随低氧时间延长而逐渐减少(慢性低氧10 d后就有显著性意义),电流- 电压关系曲线逐渐右下移。⑶急性缺氧对慢性间歇性低氧大鼠PASMCs KV电流的抑制作用随慢性间歇性低氧时间延长而逐渐减弱。上述观察结果提示慢性间歇性低氧减弱急性缺氧对 KV 的抑制, 这可能是机体低氧适应的一种重要机制。     

Silencing of STIM1 attenuates hypoxia-induced PASMCs proliferation via inhibition of the SOC/Ca2+/NFAT pathway

Background

Stromal interaction molecule 1 (STIM1) is a newly discovered Ca²⁺ sensor on the endoplasmic reticulum which is an indispensable part in the activation of store-operated Ca²⁺ channels (SOC). Recent studies demonstrate that SOC of pulmonary smooth muscle cells (PASMCs) were upregulated by chronic hypoxia which contribute to the enhanced pulmonary vasoconstriction and vascular remodeling. However, the exact role of STIM1 in the development of chronic hypoxic pulmonary hypertension(HPH) remains unclear.

Methods

In this study we investigated the cellular distribution and expression of STIM1 by immunofluorescence, qRTPCR and Western blotting methods in Wistar rat distal intrapulmonary arteries under normal and chronic hypobaric hypoxic conditions. In vitro, Wistar rat PASMCs were isolated and cultured. PASMCs were transfected with siRNA targeting STIM1 gene by liposome. The expression of STIM1 protein was detected by Western blotting. [³H]-thymidine ([³H]-TdR) incorporation were performed to detect PASMCs proliferation. The cell cycle was analyzed by flow cytometry. The SOC-mediated Ca²⁺ influx was calculated by Ca²⁺ fluorescence imaging and the nuclear translocation of NFATc3 was determined by immunofluorescence and Western blot analysis of nuclear extracts.

Results

We found that during the development of HPH and the initiation of vascular remodeling, the mRNA and protein expression levels of STIM1 significantly increased in the distal intrapulmonary arteries. Moderate hypoxia significantly promotes PASMCs proliferation and cell cycle progression. Silencing of STIM1 significantly decreased cellular proliferation and delayed the cell cycle progression induced by hypoxia. Silencing of STIM1 also significantly decreased SOC-mediated Ca²⁺ influx and inhibited the nuclear translocation of NFATc3 in hypoxic PASMCs.

Conclusion

Our findings suggest that chronic hypobaric hypoxia upregulates the expression of STIM1 in the distal intrapulmonary arteries which plays an important role in the hypoxia-induced PASMCs proliferation via SOC/Ca²⁺/NFAT pathway and may represent a novel therapeutic target for the prevention of hypoxia pulmonary hypertension.     

Chronic in ovo hypoxia decreases pulmonary arterial contractile reactivity and induces biventricular cardiac enlargement in the chicken embryo

Although chronic prenatal hypoxia is considered a major cause of persistent pulmonary hypertension of the newborn, experimental studies have failed to consistently find pulmonary hypertensive changes after chronic intrauterine hypoxia. We hypothesized that chronic prenatal hypoxia induces changes in the pulmonary vasculature of the chicken embryo. We analyzed pulmonary arterial reactivity and structure and heart morphology of chicken embryos maintained from days 6 to 19 of the 21-day incubation period under normoxic (21% O(2)) or hypoxic (15% O(2)) conditions. Hypoxia increased mortality (0.46 vs. 0.14; P < 0.01) and reduced the body mass of the surviving 19-day embryos (22.4 +/- 0.5 vs. 26.6 +/- 0.7 g; P < 0.01). A decrease in the response of the pulmonary artery to KCl was observed in the 19-day hypoxic embryos. The contractile responses to endothelin-1, the thromboxane A(2) mimetic U-46619, norepinephrine, and electrical-field stimulation were also reduced in a proportion similar to that observed for KCl-induced contractions. In contrast, no hypoxia-induced decrease of response to vasoconstrictors was observed in externally pipped 21-day embryos (incubated under normoxia for the last 2 days). Relaxations induced by ACh, sodium nitroprusside, or forskolin were unaffected by chronic hypoxia in the pulmonary artery, but femoral artery segments of 19-day hypoxic embryos were significantly less sensitive to ACh than arteries of control embryos [pD(2) (= -log EC(50)): 6.51 +/- 0.1 vs. 7.05 +/- 0.1, P < 0.01]. Pulmonary vessel density, percent wall area, and periarterial sympathetic nerve density were not different between control and hypoxic embryos. In contrast, hypoxic hearts showed an increase in right and left ventricular wall area and thickness. We conclude that, in the chicken embryo, chronic moderate hypoxia during incubation transiently reduced pulmonary arterial contractile reactivity, impaired endothelium-dependent relaxation of femoral but not pulmonary arteries, and induced biventricular cardiac hypertrophy.