细胞外氯离子浓度对大鼠ClC-1通道去激活动力学特性的影响

Effect of extracellular chloride concentration on deactivation kinetics of rat ClC-1 chloride channel

为探讨ClC 1通道的门控机制 ,实验应用爪蟾卵母细胞异源性表达大鼠野生型ClC 1(WTrClC 1)通道基因 ,并使用双电极电压钳法记录通道电流。通过改变细胞外氯离子浓度 ,采用双指数拟合的方法分析通道去激活电流 ,对其去激活门控动力学特性进行了研究。结果表明 ,降低细胞外氯离子浓度可增加快速去激活电流成分 ,减少慢速去激活成分 ;同时 ,慢速去激活和快速去激活电流的时间常数都显著减小 ,说明细胞外氯离子浓度的改变可影响通道去激活动力学参数 ,从而改变通道的门控过程。

The gating mechanism of ClC-1 chloride channel was studied in this paper by heteroexpression of rat wild type ClC-1 gene in Xenopus oocytes and by two-electrode voltage clamping technique. The deactivation gating kinetic parameters were obtained by applying two exponential fitting of the deactivating currents at various extracellular chloride concentrations. It was found that decrease in extracellular chloride concentration increased the fractional amplitude of fast deactivating component, and depressed the fractional amplitude of slow deactivating component accompanied by a decrease in fast and slow deactivating time constants.These results demonstrate that the deactivation kinetic parameters of ClC-1 are largely dependent on the extracellular chloride concentration, which induces changes in channel gating.