siRNA沉默EGLN1基因对低氧下大鼠肺动脉平滑肌细胞生长的影响

 目的:体外培养大鼠肺动脉平滑肌细胞(PASMCs),利用小干扰RNA技术转染PASMCs干扰EGLN1基因表达,检测细胞活力变化,从而验证EGLN1在PASMCs活力变化中的作用。方法:采用原代培养PASMCs,构建出特异的EGLN1 siRNA脂质体并转染到PASMCs;分别在常氧和低氧下进行细胞培养,采用Western blot 检测PASMCs的EGLN1蛋白、VEGF蛋白表达水平;用CCK-8法检测细胞活力,探讨低氧条件下沉默EGLN1基因表达后对PASMCs活力的影响。结果:低氧下PASMCs活力变化和VEGF的蛋白水平表达较常氧下增加并呈时间依赖性;EGLN1沉默后,无论低氧和常氧下,PASMCs活力变化和VEGF的蛋白水平表达均受到抑制。结论:EGLN1基因参与调控低氧下大鼠PASMCs的生长,其调节可能是通过VEGF的介导而完成的。     

缺氧对肺动脉平滑肌细胞钾通道Kv1.2、Kv1.6基因表达的影响

目的:研究不同缺氧时间对大鼠肺动脉平滑肌细胞(PASMC)不同亚型钾通道(Kv)mRNA和蛋白质表达的影响。方法:采用半定量RT-PCR和Western-blot方法对常氧和不同缺氧时间后PASMC上Kv1.2、Kv1.6mRNA和蛋白质的表达进行测定。结果:(1)PASMC在常氧和缺氧时均有Kv1.2、Kv1.6mRNA和蛋白质表达;(2)缺氧18h使Kv1.2mRNA和蛋白质表达增强,缺氧48h则使其表达减弱且低于常氧时的表达;(3)缺氧18h、48h对Kv1.6的mRNA和蛋白质表达无影响。结论:Kv1.6不是氧敏感的钾通道;作为氧感受器的Kv1.2,其mRNA和蛋白质表达随缺氧时间而改变。     

Hypoxia suppresses Kv 2.1 channel expression through endogenous 15-hydroxyeicosatetraenoic acid in rat pulmonary artery

We have previously reported that hypoxia activates lung 15-lipoxygenase (15-LOX), which catalyzes arachidonic acid to produce 15-HETE, leading to constriction of neonatal rabbit pulmonary arteries. Hypoxia suppresses Kv2.1 channel expression. Although the Kv channel inhibition by hypoxia is likely to be mediated through 15-HETE, direct evidence is still lacking. To explore whether 15-LOX/15-HETE pathway contributes to the hypoxia-induced down-regulation of Kv2.1 channel, we performed studies using 15-LOX blockers, semi-quantitative PCR and western blot analysis. We found that Kv2.1 channel expression at the mRNA and protein levels was greatly up-regulated in pulmonary arterial smooth muscle cells (PASMCs) and pulmonary artery (PA) after blockade of endogenous 15-HETE under hypoxic condition. 15-HETE further decreased Kv2.1 channel expression in comparison with 12-HETE and 5-HETE in cultured PASMCs and PA under normoxic conditions. These data indicate that hypoxia suppresses Kv2.1 channel expression through endogenous 15-HETE in PA.     

α1-肾上腺素受体在缺氧性肺动脉平滑肌细胞增殖中的作用

目的: 探讨肾上腺素α₁受体(α₁AR)及β₂受体(β₂AR)在缺氧性肺动脉平滑肌细胞(PASMCs)增殖中的作用及分子机制。方法: 用贴块法培养新生牛肺动脉平滑肌细胞至第6代,并作免疫组化染色鉴定。细胞在6.6% O₂环境中常压缺氧6、12、24 h,用 -TdR掺入法反映DNA合成测定PASMCs的增殖,用Fura-2/AM测定胞内Ca²⁺浓度。用Northern blotting法观察PASMCs的c-fos、c-myc基因表达和α₁AR mRNA、β₂AR mRNA的变化。加用不同的受体激动剂和抑制剂,探讨α₁AR被激活和抑制后,以及β₂AR激活后对上述变化的影响。结果: 单纯缺氧,PASMCs DNA合成即明显增加,α₁AR激活后,增加更明显;而α₁AR抑制后,明显降低(P<0.01)。β₂AR激活时无明显变化。缺氧后胞内游离钙浓度也增高(P<0.01),PASMCs上c-fos和c-myc基因表达增强(P<0.05),α₁AR mRNA和β₂AR mRNA水平均显著增高(P<0.01)。结论: 结果提示缺氧刺激PASMCs,使胞内钙浓度增加,c-fos和c-myc基因表达增强,引起PASMCs增殖,这一增殖是通过α₁AR介导的,但β₂AR不起主要作用。缺氧时α₁AR增多,既促进肺血管收缩,又加强细胞增殖,在缺氧性肺血管收缩和肺血管重建导致的肺动脉高压中起一定的作用     

容量激活性氯离子通道在低氧高二氧化碳处理的大鼠PASMCs的表达及其与MAPK通路的关系

 目的：探讨容量激活性氯离子通道（CLC3）在低氧高二氧化碳处理的大鼠肺动脉平滑肌细胞（PASMCs）中的表达变化及其与MAPK信号通路的关系。方法：酶消化法取雄性SD大鼠PASMCs进行原代培养,采用小鼠抗大鼠α-平滑肌肌动蛋白免疫荧光细胞化学法进行细胞鉴定;复制低氧高二氧化碳模型,采用免疫印迹法检测CLC3蛋白的表达;采用RT-PCR技术测定CLC3 mRNA水平的表达。结果：(1)与对照组比较,低氧高二氧化碳组PASMCs CLC3 mRNA和蛋白表达量均显著上调(均P＜001);(2)与低氧高二氧化碳组比较,ERK抑制剂U0126+低氧高二氧化碳组PASMCs CLC3 mRNA和蛋白表达量均显著下调(均P＜001);p38抑制剂SB203580+低氧高二氧化碳组PASMCs CLC3 mRNA和蛋白表达量均明显上调(均P＜001);p38激活剂茴香霉素+低氧高二氧化碳组PASMCs CLC3 mRNA和蛋白表达水平均显著下降(P＜005和P＜001)。结论：低氧高二氧化碳可上调大鼠PASMCs CLC3 mRNA和蛋白的表达;ERK1/2通路介导了低氧高二氧化碳诱导的大鼠PASMCs CLC3表达, 而p38 MAPK通路活化则下调低氧高二氧化碳诱导的CLC3 mRNA和蛋白表达。     

三七皂苷单体R1 抑制低氧高二氧化碳诱导的肺动脉平滑肌细胞p38 MAPK信号通路的活化

目的: 探讨三七皂苷单体R₁(R₁)减轻低氧高二氧化碳(CO₂)性肺动脉收缩的作用及其与p38 MAPK信号通路的关系。方法: 原代培养雄性SD大鼠肺动脉平滑肌细胞(PASMCs),取第2至5代对数生长期细胞至低氧高CO₂(1% O₂, 6% CO₂)条件下继续培养,并分别用8、40、100 mg/L R₁ 孵育24 h后收集细胞,采用免疫印迹法测定p38 MAPK磷酸化蛋白表达,半定量RT-PCR检测p38 MAPK mRNA的表达。结果: Western blotting和RT-PCR结果显示,低氧高CO₂组p-p38 MAPK蛋白和p38 MAPK mRNA表达明显高于对照组(N)组(P<0.01)。与低氧高CO₂组相比,R₁(8、40、100 mg/L)不同程度抑制了p-p38 MAPK蛋白和p38 MAPK mRNA的表达(P<0.01),并呈剂量依赖关系。结论: 低氧高CO₂诱导PASMCs p38 MAPK活化,三七皂苷单体R₁可能通过抑制p38 MAPK通路减轻低氧高CO₂性肺动脉收缩。     

Hypoxia inhibits myosin phosphatase in pulmonary arterial smooth muscle cells: role of Rho-kinase

Rho-kinase was recently found to phosphorylate the myosin-binding subunit (MBS) of myosin phosphatase (MP) and to regulate MP activity. Although myosin light chain (MLC) phosphorylation in pulmonary arterial smooth muscle cells (PASMCs) is thought to be the cellular/molecular basis for hypoxic pulmonary vasoconstriction (HPV), very little is known about the role that Rho-kinase/MP plays in HPV. Rat PASMCs were cultured and made hypoxic (PO2 = 23 +/- 2 mm Hg). Cells exposed to normoxia (PO2 approximately 148 mm Hg) served as controls. PASMCs exposed to hypoxia showed a significant increase in MLC and MBS phosphorylation, and a significant decrease in MP activity. Rho-kinase inhibitors (HA1077 or Y-27632) blocked hypoxia-induced MP inactivation and inhibited the hypoxia-induced MLC phosphorylation. Hypoxia was also found to induce stress fiber formation and actin polymerization in cultured PASMCs. In summary, these data show that MP inhibition in PASMCs is linked to activation of Rho-kinase, and that hypoxia inhibits the MP signaling pathway via Rho-kinase.     

Subacute hypoxia decreases voltage-activated potassium channel expression and function in pulmonary artery myocytes

Chronic hypoxia results in both structural changes in the pulmonary artery and a sustained increase in pulmonary vascular tone. This study investigated the effects of subacute moderate hypoxia on expression and function of potassium (K+) channels in rat pulmonary artery myocytes (PASMCs). The rats were kept at 0.67 atmospheres for 6, 12, or 24 h. We found that the expression of mRNA for voltage-activated K+ channels (Kv)1.2, Kv1.5, and Kv2.1 is reduced after less than 24 h of this moderate hypoxia. K+ current (Ik) is significantly inhibited in PASMCs from rats hypoxic for 24 h, resting membrane potential is depolarized and cytosolic [Ca2+] is increased in these cells. In addition, antibodies to Kv1.2, Kv1.5, and Kv2.1 inhibit Ik, cause membrane depolarization and attenuate both hypoxia- and 4-AP-induced elevation in [Ca2+]i in PASMCs from normoxic rats but not from 24 h hypoxic rats. Subacute hypoxia does not completely remove the mRNA for Kv1.2, Kv1.5, and Kv2.1, but antibodies against these channels no longer alter Ik or cytosolic calcium, suggesting that subacute hypoxia may inactivate the channels as well as reduce expression. As the expression of mRNA for Kv1.2, Kv1.5, and Kv2.1 is sensitive to subacute hypoxia and decreased expression/function of these channels has physiologic effects on membrane potential and cytosolic calcium, it seems likely that these Kv channels may also be involved in the mechanism of high-altitude pulmonary edema and possibly in the signaling of chronic hypoxic pulmonary hypertension.     

活性氧和ERK1/2信号通路在缺氧大鼠肺动脉平滑肌细胞增殖和凋亡中的作用

目的：研究缺氧状态下大鼠肺动脉平滑肌细胞（PASMCs）内活性氧（ROS）水平的变化,ROS对细胞外信号调节激酶（ERK）1/2蛋白表达的影响以及ROS和ERK1/2在PASMCs增殖和凋亡关系失衡中的作用。方法: 原代培养正常大鼠PASMCs,选用第2-3代用于实验。分别在常氧及缺氧条件下用ROS清除剂tiron、ERK1/2抑制剂PD98059进行分组干预。通过NBT还原法和DCFH-DA荧光探针检测细胞内ROS,免疫荧光法检测磷酸化- ERK1/2（p-ERK1/2）蛋白表达,MTT比色法和增殖细胞核抗原（PCNA）蛋白的免疫细胞化学法检测细胞增殖,原位末端标记法（TUNEL）检测细胞凋亡。结果: (1)缺氧组细胞内ROS水平明显高于对照组（P<0.01）;(2)缺氧组的增殖活性与对照组相比显著增高（P<0.01）,而凋亡率显著降低（P<0.01）,使用tiron后能明显抑制缺氧诱导的细胞增殖（P<0.05）,而凋亡率却明显升高（P<0.01）;(3)缺氧组p-ERK1/2蛋白表达显著高于对照组（P<0.01）,使用tiron后缺氧诱导的p-ERK1/2表达被显著抑制（P<0.01）;(4)使用PD98059也能明显抑制缺氧诱导的细胞增殖（P<0.05）,而凋亡率也明显升高（P<0.01）,缺氧下同时使用PD98059和tiron与单用tiron相比,对细胞增殖和凋亡的影响均无明显差异（P>0.05）。结论: 缺氧时PASMCs中生成增多的ROS通过活化下游ERK1/2信号通路,促进PASMCs增殖并抑制凋亡,从而在缺氧性肺动脉重建过程中发挥重要作用。     

Role of oxygen availability in CFTR expression and function

The cystic fibrosis transmembrane conductance regulator (CFTR) serves a pivotal role in normal epithelial homeostasis; its absence leads to destruction of exocrine tissues, including those of the gastrointestinal tract and lung. Acute regulation of CFTR protein in response to environmental stimuli occurs at several levels (e.g., ion channel phosphorylation, ATP hydrolysis, apical membrane recycling). However, less information is available concerning the regulatory pathways that control levels of CFTR mRNA. In the present study, we investigated regulation of CFTR mRNA during oxygen restriction, examined effects of hypoxic signaling on chloride transport across cell monolayers, and related these findings to a possible role in the pathogenesis of chronic hypoxic lung disease. CFTR mRNA, protein, and function were robustly and reversibly altered in human cells in relation to hypoxia. In mice subjected to low oxygen in vivo, CFTR mRNA expression in airways, gastrointestinal tissues, and liver was repressed. CFTR mRNA expression was also diminished in pulmonary tissues taken from hypoxemic subjects at the time of lung transplantation. Environmental factors that induce hypoxic signaling regulate CFTR mRNA and epithelial Cl(-) transport in vitro and in vivo.     

Mitogen activated protein kinase (MAPK) pathway regulates heme oxygenase-1 gene expression by hypoxia in vascular cells

Hypoxia induces the stress protein heme oxygenase-1 (HO-1), which participates in cellular adaptation. The molecular pathways that regulate ho-1 gene expression under hypoxia may involve mitogen activated protein kinase (MAPK) signaling and reactive oxygen. Hypoxia (8 h) increased HO-1 mRNA in rat pulmonary aortic endothelial cells (PAEC), and also activated both extracellular signal-regulated kinase 1 (ERK1)/ERK2 and p38 MAPK pathways. The role of these kinases in hypoxia-induced ho-1 gene expression was examined using chemical inhibitors of these pathways. Surprisingly, SB203580, an inhibitor of p38 MAPK, and PD98059, an inhibitor of mitogen-activated protein kinase kinase (MEK1), strongly enhanced hypoxia-induced HO-1 mRNA expression in PAEC. UO126, a MEK1/2 inhibitor, enhanced HO-1 expression in PAEC under normoxia, but not hypoxia. Diphenylene iodonium, an inhibitor of NADPH oxidase, also induced the expression of HO-1 in PAEC under both normoxia and hypoxia. Similar results were observed in aortic vascular smooth muscle cells. Furthermore, hypoxia induced activator protein (AP-1) DNA-binding activity in PAEC. Pretreatment with SB203580 and PD98059 enhanced AP-1 binding activity under hypoxia in PAEC; UO126 stimulated AP-1 binding under normoxia, whereas diphenylene iodonium stimulated AP-1 binding under normoxia and hypoxia. These results suggest a relationship between MAPK and hypoxic regulation of ho-1 in vascular cells, involving AP-1.     

慢性阻塞性肺疾病合并慢性缺氧患者肺动脉平滑肌细胞电压门控钾通道亚型基因表达的变化

目的：探讨人肺动脉平滑肌细胞（PASMCs）的几种Kv通道亚型：Kv1.2、 Kv1.3、Kv1.5、Kv2.1、Kv3.1等，在COPD合并慢性缺氧时基因表达的变化。旨在探索预防人类肺源性心脏病的发生和找到新的防治方法提供试验依据。 方法： 从手术室切取人正常肺组织、单纯COPD患者和COPD合并慢性缺氧患者肺组织，将标本分为：①正常对照的PASMCs、单纯COPD和COPD合并慢性缺氧患者的PASMCs；②正常对照的PASMCs和经过慢性缺氧培养的PASMCs。利用半定量RT-PCR技术，分析Kv1.2、Kv1.3、Kv1.5、Kv2.1、Kv3.1等的基因表达。 结果： ①Kv1.2、Kv1.3、Kv1.5、Kv2.1、Kv3.1等基因在正常PASMCs和单纯COPD患者PASMCs中均有表达，而且两者无显著差异；②Kv1.2、Kv1.5、Kv2.1在患者在体慢性缺氧和离体慢性缺氧时的表达均明显降低（P<0.05）；Kv1.3在患者在体慢性缺氧时表达明显降低（P<0.05），而离体慢性缺氧时无显著变化（P>0.05）；Kv3.1在患者在体慢性缺氧和离体慢性缺氧时的表达均无显著变化（P>0.05）；③Kv1.2、Kv1.5、Kv2.1、Kv3.1等基因在单纯COPD时表达显著上调（P<0.05）。 结论： 在慢性缺氧情况下，Kv1.2、Kv1.3、Kv1.5、Kv2.1 4种亚型基因表达明显下降，提示可能在促进人肺动脉高压的形成和发展中起重要作用。而慢性缺氧对Kv3.1基因表达无显著影响，提示它们可能对缺氧不敏感，在人肺动脉高压发生中处于次要地位。至于在单纯COPD时几种亚型的表达上调，原因不清楚，需进一步研究证实。     

人参皂甙Rb1通过Rho/Rho激酶通路影响低氧诱导大鼠肺动脉平滑肌细胞增殖及SERT和5-HT_(1B)R表达

目的:观察人参皂甙Rb1对低氧性大鼠肺动脉平滑肌细胞(PASMCs)5-羟色胺转运体(SERT)和5-羟色胺1B受体(5-HT_(1B)R)表达及细胞增殖的影响,并探讨Rho/Rho激酶通路在其中的作用。方法:分离并培养健康雄性SD大鼠PASMCs,随机分为常氧组(normal组)、低氧组(hypoxia组)以及低氧加50、100和200 mg/L人参皂甙Rb1组(HR50、HR100和HR200组),采用CCK-8、Brd U结合流式细胞术、Western blot及RT-PCR等方法,观察大鼠PASMCs的增殖程度以及SERT和5-HT_(1B)R的mRNA和蛋白表达变化;另取PASMCs分为normal组、hypoxia组、HR200组和低氧加Y-27632组(HY组),检测Rho激酶(ROCK1)mRNA表达和肌球蛋白磷酸酶目标亚单位1(MYPT1)磷酸化水平。结果:与normal组比较,hypoxia组PASMCs增殖明显(P0.01);与hypoxia组比较,人参皂甙Rb1可明显抑制PASMCs的增殖(P0.01),并浓度依赖性抑制SERT和5-HT_(1B)R的mRNA与蛋白表达(P0.05);HR200组可明显抑制ROCK1的mRNA表达和MYPT1磷酸化水平(P0.01),与HY组相比较,差异无统计学显著性。结论:低氧能诱导大鼠PASMCs增殖,上调SERT和5-HT_(1B)R表达;人参皂甙Rb1能浓度依赖性抑制这种作用,其机制可能与抑制Rho/Rho激酶通路表达有关。     

Contribution of myocardin in the hypoxia-induced phenotypic switching of rat pulmonary arterial smooth muscle cells

BackgroundHypoxic exposure contributes to the phenotypic switching of smooth muscle cells (SMCs), while the mechanisms involved in this process is not yet fully elucidated. Myocardin as a co-actor of serum reaction factor plays a crucial role in differentiation of SMCs. This study was aimed to investigate the role of myocardin in hypoxia-induced phenotypic switching of rat pulmonary arterial SMCs (PASMCs).MethodsPrimary PASMCs were cultured under normoxia and hypoxia (3%O₂, 48 h) respectively, and then the cell proliferation was assessed and the expression of SM22α, osteopontin (contractile and synthetic marker of SMCs, respectively), myocardin and platelet-derived growth factor-BB (PDGF-BB) were detected. After pGCSIL-GFP-shMYOCD lentviral vector was transduced to the PASMCs, the expression of myocardin and SM22α were examined. Moreover, myocardin expression in PASMCs treated with medium enriched with PDGF-BB and conditional medium (CM) from normoxia- and hypoxia-exposed PASMCs was assessed.ResultsExposing PASMCs to hypoxia led to an increased cell numbers and the up-regulation of proliferating cell nuclear antigen (PCNA), osteopontin and PDGF-BB; moreover, a significant down-regulation of SM22α and myocardin was identified. Further analysis revealed that knock-down of myocardin with pGCSIL-GFP-shMYOCD vector followed by a decreased SM22α in the PASMCs, and treatment of PASMCs with either exogenous PDGF-BB or hypoxic CM led to a marked decrease of myocardin.ConclusionsOur findings suggest that the decrease of myocardin in PASMCs exposed to hypoxia is partly regulated by the increase of PDGF-BB, which contributes to the phonotypic switching of PASMCs in hypoxic condition.     

Hypoxic induction of cox-2 regulates proliferation of human pulmonary artery smooth muscle cells

Chronic hypoxia-induced pulmonary hypertension results partly from proliferation of smooth muscle cells in small peripheral pulmonary arteries. Therefore, we examined the effect of hypoxia on growth of pulmonary artery smooth muscle cells (PASMCs) from human distal pulmonary arteries. Initial studies identified that serum-induced proliferation of explant-derived PASMCs was inhibited under hypoxic conditions (3-4 kPa in medium). However, selection of hypoxia-stimulated cells was achieved by culturing cells at low density under conditions of prolonged hypoxia (1-2 wk). In hypoxia-inhibited and -stimulated cells, Western blotting revealed hypoxic induction of cyclooxygenase (COX)-2, which was dependent on the activation of p38(MAPK), but not COX-1, inducible nitric oxide synthase (iNOS), or hemoxygenase-1 (HO-1). Hypoxic induction of COX-2 was also observed in the media of pulmonary arteries in lung organ culture. Hypoxia induced a 4- to 5-fold increase (P < 0.001) in prostaglandin (PG)E(2), PGD(2), PGF(2alpha), and 6-keto-PGF(1alpha) release from PASMCs. Hypoxic inhibition of proliferation was attenuated by incubation with indomethacin (10 micro M), or the COX-2 antagonist, NS398 (10 micro M), but not by the COX-1 antagonist, valeryl salicylate (0.5 mM). In conclusion, we have isolated cells from human peripheral pulmonary arteries that are either inhibited or stimulated by culture under hypoxic conditions. In both cell types hypoxia modulates cell proliferation by induction of COX-2 and production of antiproliferative prostaglandins. Induction of COX-2 may contribute to the inhibition of hypoxia-induced pulmonary vascular remodeling.     

缺氧对肺动脉成纤维细胞MMP-2、TIMP-1表达的影响

目的：探讨缺氧对肺动脉成纤维细胞（Fpa）分泌基质金属蛋白酶（MMPs）、金属蛋白酶组织抑制剂（TIMPs）的影响。 方法： 采用酶谱法测定Fpa培养基中MMP-2的酶活性，免疫印迹法检测培养基中MMP-2、TIMP-1 的蛋白水平，免疫组化法测定细胞原位的蛋白表达， RT-PCR法检测mRNA表达量。 结果： 缺氧后Fpa分泌的MMP-2酶活性、细胞内外蛋白表达量、mRNA表达量均下降；而TIMP-1的表达则呈相反变化。 结论： 缺氧可使肺动脉成纤维细胞MMP-2/TIMP-1的表达失衡，可能参与缺氧性肺血管重建。     

Inhibition of hypoxia-induced proliferation of pulmonary arterial smooth muscle cells by a mTOR siRNA-loaded cyclodextrin nanovector

The proliferation of pulmonary arterial smooth muscle cells (PASMCs) is a key pathophysiological component of vascular remodeling in pulmonary arterial hypertension (PAH), an intractable disease, for which pharmacotherapy is limited and only slight improvement in survival outcomes have achieved over the past few decades. RNA interference provides a highly promising strategy to the treatment of this chronic lung disease, while efficient delivery of small interfering RNA (siRNA) remains a key challenge for the development of clinically acceptable siRNA therapeutics. With the aim to construct useful nanomedicines, the mammalian target of rapamycin (mTOR) siRNA was loaded into hybrid nanoparticles based on low molecular weight (Mw) polyethylenimine (PEI) and a pH-responsive cyclodextrin material (Ac-aCD) or poly(lactic-co-glycolic acid) (PLGA). This hybrid nanoplatform gave rise to desirable siRNA loading, and the payload release could be modulated by the hydrolysis characteristics of carrier materials. Fluorescence observation and flow cytometry quantification suggested that both Ac-aCD and PLGA nanovectors (NVs) may enter PASMCs under either normoxia or hypoxia conditions as well as in the presence of serum, with uptake and transfection efficiency significantly higher than those of cationic vectors such as PEI with Mw of 25 kDa (PEI25k) and Lipofectamine 2000 (Lipo 2k). Hybrid Ac-aCD or PLGA NV containing siRNA remarkably inhibited proliferation and activated apoptosis of hypoxic PASMCs, largely resulting from effective suppression of mTOR signaling as evidenced by significantly lowered expression of mTOR mRNA and phosphorylated protein. Moreover, these hybrid nanomedicines were more effective than commonly used cationic vectors like PEI25k and Lipo 2k, with respect to cell growth inhibition, apoptosis activation, and expression attenuation of mTOR mRNA and protein. Therefore, mTOR siRNA nanomedicines based on hybrid Ac-aCD or PLGA NV may be promising therapeutics for diseases related to hypoxic abnormal growth of PASMCs.     

缺氧对大鼠肺动脉平滑肌细胞 HO-1 基因表达和内源性一氧化碳生成的影响

目的:研究缺氧对体外培养的大鼠肺动脉平滑肌细胞诱导型血红素氧合酶(HO-1)基因表达及内源性一氧化碳(CO)产生的影响,探讨HO-CO系统在缺氧性肺动脉高压中的作用。方法:原代培养大鼠肺内动脉的平滑肌细胞(PASMC)并传代,选用第3-5代PASMC用于实验。在培养瓶内通缺氧气体(95%N₂,5%CO₂)12、24h和48h后,用逆转录-聚合酶链式反应(RT-PCR)检测PASMC中HO-1mRNA水平,用酶联免疫检测仪测定培养基中碳氧血红蛋白(COHb)含量,放免法测定培养基中环磷酸鸟苷(cGMP)含量。结果:缺氧12、24和48hHO-1mRNA分别较正常对照组高2.7%、5.7%和27.1%(P＜0.01),培养基中COHb的含量分别较正常对照组高13.8%、31.0%和93.1%(P＜0.01),PASMC中cGMP的含量分别为正常对照组的2.7、4.0和6.8倍(P＜0.01或P＜0.05)。结论:缺氧诱导PASMC中的HO-1基因表达上调,并使内源性CO产生增多,对PASMC内cGMP浓度有调节作用。     

BQ123对大鼠肺动脉平滑肌细胞电压门控钾通道表达的影响

目的：探讨内皮素-1受体拮抗剂BQ123 对大鼠肺动脉平滑肌细胞电压门控钾通道亚型基因表达的影响。 方法： 根据常氧 (PO2 152 mmHg ) 及慢性低氧（PO2 40±5 mmHg）的不同培养条件，将肺动脉平滑肌细胞分为常氧组和慢性低氧组，并用BQ123分别处理上述两组细胞，采用半定量RT-PCR技术检测大鼠肺动脉平滑肌细胞Kv2.1、Kv9.3基因表达的变化。 结果： 经过慢性低氧，大鼠肺动脉平滑肌细胞Kv2.1、Kv9.3的mRNA表达水平明显低于常氧组（P<0.01，n=5），BQ123对常氧组Kv2.1的mRNA表达无影响（P>0.05，n=5），但可明显增加慢性低氧组Kv2.1的表达（P<0.01，n=5）。无论在常氧还是慢性低氧时，BQ123对Kv9.3的mRNA表达均无影响（P>0.05，n=5）。 结论： 慢性低氧可降低大鼠肺动脉平滑肌细胞电压门控钾通道的表达，内皮素-1受体拮抗剂BQ123可能通过抑制PASMCs的增殖，改变了细胞内信号转导通路中某些因子的表达，从而间接促进Kv的表达。     

Ca2+ and ion channels in hypoxia-mediated pulmonary hypertension

Alveolar hypoxia, a consequence of many lung diseases, can have adverse effects on the pulmonary vasculature. The changes that occur in the pulmonary circulation with exposure to chronic hypoxia include reductions in the diameter of the pulmonary arteries due to structural remodeling of the vasculature. Although the structural and functional changes that occur in the development of pulmonary hypertension have been well investigated, less is known about the cellular and molecular mechanisms of this process. This review will discuss the role of several potassium and calcium channels in hypoxic pulmonary vasoconstriction, both in elevating calcium influx into pulmonary artery smooth muscle cells (PASMCs). In addition to other signal transduction pathways, Ca²⁺ signaling in PASMCs plays an important role in the development and progression of pulmonary hypertension due to its central roles in vasoconstriction and vascular remodeling. This review will focus on the effect of chronic hypoxia on ion channels and the potential pathogenic role of Ca²⁺ signaling and regulation in the progression of pulmonary hypertension.