肾上腺髓质瘤无性繁殖细胞延时整流钾离子通道的门控动力学

KINETIC PROPERTY OF A DELAYED RECTIFIER POTASSIUM CHANNEL IN PC12 CELLS

用片膜钳技术在细胞贴附式和内面向外式的膜片上观察和分析了作者新近发现的PC12细胞上的延时整流钾通道的开放与关闭规律:开放时间分布直方图由双指数密度函数拟合,关闭时间分布直方图也由两个指数密度函数拟合;随着去极化的增大,首次开放潜伏期缩短,通道开放概率增大,表明有明显的电压依赖性。在通道串式开放簇之间常有一个长时间的关闭,表明通道还有一个很慢的门控过程。据此,提出一个含有两个开放状态与3个关闭状态的模型。

Authors have reported that there is a delayed rectifier potassium channel in the pheochromocytoma(PC12)cells. The durations of open and closed events of the channel were measured by using the cell-attached or inside-out configurations of the patch-clamp method. The open time histogram could be fit by a function with two exponential components. The closed time histogram could also be fit by a function with two exponential components. The channel showed steep voltage-dependence, when increasing depolarization, the first latencies became shorter, and the open probability of the channel also increased. There is long close(s) among the bursts of openings, which shows that the channel has also a slow gating process. A scheme containing two open states and three closed states is proposed.