钾离子通道在不同胎龄大鼠动脉导管收缩的作用.docVIP

钾离子通道在不同胎龄大鼠动脉导管收缩的作用 【摘要】 目的 研究大鼠动脉导管平滑肌中的三磷酸腺苷（ATP）敏感的钾离子通道（KATP）及电压依赖的钾通道（Kv）的发育变化及其在动脉导管收缩中的作用。方法 通过测量胎龄19天（早产）及21天（足月）（n=8）胎鼠动脉导管血管环张力及利用全细胞膜片钳技术方法测量动脉导管单个平滑肌细胞的钾离子电流，观察KATP激动剂吡拉地尔和KATP阻断剂格列本脲，Kv阻断剂4-氨基吡啶对动脉导管收缩和钾离子电流的影响。结果 格列本脲可收缩胎龄21天胎鼠的动脉导管，但对19天的无作用。钾电流可以因吡拉地尔增加，因格列本脲减少，但这种减少的电流在胎龄21天的动脉导管要明显大于19天的。4-氨基吡啶在两组作用无明显差异。结论 本研究数据提示在早产儿与足月儿比较，总的Kv电流无明显差异，但KATP电流明显减少，KATP通道未发育成熟，支持KATP在动脉导管平滑肌作为一个氧感受器，是早产儿动脉导管未闭发生率高的原因之一。 【关键词】 动脉导管；氧气；钾离子通道；早产儿 The role of potassium channels in oxygen-induced contraction of ductus arteriosus in fetal rat of different gestation age 【Abstract】 Objective To investigated the role of ATP sensitive potassium channel and voltage-dependent potassium channel in oxygen-induced contraction of ductus arterioses of rat. Methods Isometric force of contact tissue and potassium current in single smooth muscle cells of ductus arteriosus were measured in two groups of rats of 19th (premature) and 21st (mature) gestation age respectively. The effects of pinacidil(KATP activater)， glybenclamide (KATP inhibitor)， and 4-aminopyridine(KV inhibitor) were investigated.Results glybenclamide contracted ductus arteries in 21st group but not in 19th group. Potassium current increased by applying pinacidil in the perfusion solution and decreased by glybenclamide.The change of the currents， together with the depolarization of the membrane potential were significant greater in 21st group then in 19th group. No significant different effect of 4-aminopyridine was observed between two groups.Conclusion KATP but not KV channel may be one of the O2 sensors in ductus arterioses. It was underdeveloped in premature fetus. and participate in their poor reaction to oxygen and high incidence of patent ductus arteriosus. 【Key words】 ductus arteriosus； oxygen； potassium channel； premature fetus 新生儿的动脉导管通常在生后数小时到数日关闭。出生后随着呼吸的开始，血氧分压升高是动脉导管收缩的重要原因。早产儿动脉导管对氧浓度变化的反应欠佳，与早产儿动脉导管对氧的敏感性尚未成熟有关。提高灌流液氧分压可引起离体动脉导管收缩。这种氧气引发的动脉