【摘要】 目的:探讨细胞浆内游离钙离子浓度([Ca2+]i)在常氧、急性和慢性低氧条件下对大鼠肺动脉平滑肌细胞(PASMCs)膜钙激活氯离子通道(ClCa)的调节作用。方法:常规离体血管灌流法检测急性低氧时肺动脉环张力变化;钙荧光探针(Fura-2/AM)负载培养PASMCs,观察常氧和慢性低氧条件下[Ca2+]i的变化并由此对ClCa的影响;同时用四唑盐(MTT)比色法观察当[Ca2+]i变化时ClCa对PASMCs增殖的影响。结果:(1)ClCa阻断剂尼氟灭酸(NFA)和indaryloxyaceticacid(IAA-94)可以舒张急性低氧引起的肺动脉环收缩。(2)慢性低氧时[Ca2+]i升高:常氧状态下,PASMCs[Ca2+]i为(123.63±18.98)nmol/L,低氧时为(281.75±16.48)nmol/L(P<0.01)。(3)常氧时,NFA和IAA-94对[Ca2+]i无明显影响(P>0.05)。(4)慢性低氧时,NFA和IAA-94使PASMCs[Ca2+]i由(281.75±16.48)nmol/L降低到(117.66±15.36)nmol/L(P<0.01)。(5)MTT比色法中,慢性低氧状态下NFA和IAA-94引起升高的吸光度(A)值降低,由0.459±0.058到0.224±0.025(P<0.01)。结论:低氧引起[Ca2+]i升高,这可能激活ClCa,对[Ca2+]i起正反馈作用,ClCa可能在低氧肺动脉高压中起作用;慢性低氧条件下ClCa可能参与促进大鼠PASMCs的增殖。更多还原

【Abstract】 AIM: To investigate the role of intracellular free Ca2+ concentration ([Ca2+]i) in the regulation of calcium-activated chloride (ClCa) channels in pulmonary artery smooth muscle cells (PASMCs) of rats under normoxic, acute and chronic hypoxic conditions. METHODS: Acute hypoxia-induced contraction was observed in rat pulmonary artery by using routine blood vascular perfusion in vitro. The fluorescence Ca2+ indicator Fura-2/AM was used to observe [Ca2+]i of rat PASMCs in normal and chronic hypoxic condition. The influences of ClCa channels on PASMCs proliferation were assessed by MTT assay. RESULTS: (1) The ClCa channel blockers niflumic acid (NFA) and indaryloxyacetic acid (IAA-94) produced inhibitory effects on acute hypoxia-evoked contractions in pulmonary artery. (2) Under chronic hypoxic condition, [Ca2+]i was increased. In normoxic condition, [Ca2+]i was (123.63±18.98) nmol/L, and in hypoxic condition, [Ca2+]i was (281.75±16.48)nmol/L (P<0.01). (3) In normoxic condition, [Ca2+]i had no significant change and no effect on ClCa channels was observed (P>0.05). (4) Chronic hypoxic increased [Ca2+]i which opened ClCa channels. The NFA and IAA-94 blocked them and decreased [Ca2+]i from (281.75±16.48)nmol/L to (117.66±15.36)nmol/L (P<0.01). (5) MTT assay showed that in chronic hypoxic condition NFA and IAA-94 decreased the value of absorbing light degree (A value) from 0.459±0.058 to 0.224±0.025 (P<0.01). CONCLUSION: Hypoxia increased [Ca2+]i which opened ClCa channels and had a positive-feedback to [Ca2+]i. This may play an important role in hypoxic pulmonary hypertension. In chronic hypoxic condition, ClCa channel may play a role in the regulation of PASMCs proliferation.更多还原