小脑皮质神经元K^+单通道电流的生理特性

PHYSIOLOGICAL CHARACTERISTICS OF SINGLE K+ CHANNEL CURRENTS (Ik) IN CEREBELLAR CORTICAL NEURONS OF NEONATAL RAT

用膜片钳技术的细胞贴附式和内面向外式，在分离培养的新生大鼠小脑皮质颗粒细胞膜上记录到钾离子通道电流，有以下的生理特性，最常见的通道电导为２５ｐＳ，单通道电流幅度、开放时间、开放概率均受膜电位控制，通道开放时间分布直方图可用双指数拟合，无时间依赖性失活，不依赖钙离子，能被ＴＥＡ阻断，表明此通道可能为延迟整流型Ｋ＋通道。提示，小脑皮质颗粒细胞存在有不失活的２５ｐＳ钾离子通道，不同于文献报道的，可能是一种新亚型的钾离子通道。

The characteristics of single K + channels in cultured cerebellar granule neurons of neonatal rat were studied by the cell attached and inside out configurations of patch clamp technique.The results are as follows : the predominant conductance of single channel was 25PS, the currents amplitude, the mean open time and the open probability were dependent of membrane potential , the open time distribution histograms were fitted by two exponential components, the channel activity was not inactivated during 20s period, independent of calcium and blocked by tetraethylammonium. These results indicated that the single channel was a delayed rectifier(Ik) . It is suggested that the non inactivating channel with conductance of 25pS which exists in the cerebellar granule cell might be a new subtype of Ik channel.