兔心室肌细胞外向整流性氯电流的研究

The study of outwardly rectifying chloride current in rabbit ventricular cells

目的探讨兔心室肌细胞上外向整流性氯电流的特性。方法应用全细胞膜片钳技术记录兔心室肌单个细胞的电流。分别替代钾离子、氯离子,螯合钙离子,以及加入不同电流通道阻滞剂,观察不同条件下电流的变化。结果特定条件下,阻断兔心室肌细胞钾和钙电流后,移除胞外钙离子后加入EGTA可以引出一个明显的外向整流性的外向电流,被钙离子抑制;主要载流离子为氯离子,替代钾离子对电流影响不大;可以被氯离子阻滞剂氟灭酸阻滞;利用EGTA螯合钙离子以后,电流幅度与EGTA浓度表现出一定的浓度依赖性。结论此电流可能是钙离子抑制的氯电流。它是快激活、慢失活并且呈电压依赖性。

Objective To explore the character of the outwardly rectifying chloride current. Method Ion currents of rabbit ventricular myocyte were recorded using the whole cell patch clamp technique. Detected the changes of the current in various conditions including that：substituting K ^＋ with Cs^＋ or Cl^- with MES, using EGTA to cheated Ca^2＋ , and adding various blokers of ion channels to the solution. Result The rabbit ventricular cell responded to removal of external calcium with huge outward flow of currents. Readdition of Ca^2＋ immediately inactivated the channels. These channels were inhibited by the Cl^- channel blocker Flufenamic acid; Substitution of Cl^- with MES inhibited the channel while substituting K^＋ with Cs was without any effect. The current revealed an altered sensitivity to external Ca^2＋ concentrations. Conclusion This channel may be a Cl^- channel inhibited by Ca^2＋.