内皮素对大鼠肺动脉平滑肌细胞膜钾通道的影响  

Inhibition of voltage-gated K^+ current in rat intrapulmonary arterial smooth muscle cells by endothelin-1

作　　者：樊再雯[1] 张珍祥[1] 徐永健[1] 

机构地区：[1]华中科技大学同济医学院附属同济医院卫生部呼吸系疾病重点实验室,湖北武汉430030

出　　处：《药学学报》2004年第1期9-12,共4页Acta Pharmaceutica Sinica

基　　金：国家自然科学基金资助项目 (3 9970 3 3 2 )

摘　　要：目的　观察内皮素 (ET 1)对大鼠肺动脉平滑肌细胞 (PASMCs)膜电压门控钾通道 (KV)的作用。方法　用全细胞膜片钳记录方法研究ET 1对膜电位 (Em)、膜电容 (Cm)、电压门控钾电流 (IKV)的影响。结果　ET 1可引起PASMCs去极化 ,并抑制IKV,抑制IKV 时间明显早于其对Em 变化的影响 ,ET 1对IKV 的影响呈可逆性和浓度依赖性 ,在有钙的环境中 ,ET 1对IKV 峰电流的抑制率明显高于无钙时。结论　ET 1可浓度依赖性的抑制IKV ,使常氧大鼠PASMCs去极化 ,且ET 1对IKV 的抑制作用早于对Em 的影响 ,这些作用不完全依赖于钙的参与 ,但钙可加强ET 1对IKV 的抑制作用。Aim To investigate the role of endothelin 1 (ET 1) in the physiological and pathophysiological regulating mechanisms of voltage gated K + current (IK V) inhibition in rat intrapulmonary arterial smooth muscle cells (PASMCs). Methods Single PASMCs were obtained with acute enzyme (collagnase plus papain) dispersing method. Using whole cell patch clamp technique in freshly isolated rat PASMCs, the effect of ET 1 on voltage gated K + current was recorded. Results ET 1 (1×10 -9 mol·L -1 ) and the voltage dependent K + (K V) channel antagonist 4 aminopyridine (4AP), but not the Ca 2+ activated K + channel antagonist tetraethylammonium (TEA), caused membrane depolarization. The effect of ET 1 on membrane potential persisted in cells in which intracellular Ca 2+ was buffered with 1,2 bis (2 aminophenoxy) ethane N , N , N ′, N ′ tetraacetic acid (BAPTA). ET 1 (1×10 -9 mol·L -1 ) caused a significant reversible inhibition of K V current, which began 4 0 s after application of ET 1, was much earlier than the effect of membrane depolarization of PASMCs (15 s). ET 1 (1×10 -10 to 1×10 -7 mol·L -1 ) caused a concentration dependent inhibition of K + current (+50 mV, from 136 to 40 pA/pF). The percent inhibition was 71% at 1×10 -7 mol·L -1 ( n =6). The effect of ET 1 (1×10 -9 mol·L -1 ) on K + current was weaker under conditions free of Ca 2+ than containing Ca 2+ . At a test potential of +50 mV, free of Ca 2+ conditions reduced the maximum inhibitory effect of ET 1 from 71% to 50%. Conclusion ET 1 modulated pulmonary vascular reactivity by depolarizing membrane potential and inhibiting the K + current of PASMCs. The effect of ET 1 on PASMCs membrane potential and the inhibition of K + current were independent of Ca 2+ , but the inhibition of K + current was much greater under conditions containing Ca 2+ than free of Ca 2+ .

关 键 词：内皮素 大鼠 肺动脉平滑肌细胞 钾通道 膜片钳 慢性低氧性肺动脉高压 

分 类 号：R543.2[医药卫生—心血管疾病]