Nakajima S, Kusano K
J Gen Physiol. 1966 Mar;49(4):613-28. doi: 10.1085/jgp.49.4.613.
Depolarizations applied to voltage-clamped cells bathed in the normal solution disclose an initial inward current followed by a delayed outward current. The maximum slope conductance for the peak initial current is about 30 times the leak conductance, but the maximum slope conductance for the delayed current is only about 10 times the leak conductance. During depolarizations for as long as 30 sec, the outward current does not maintain a steady level, but declines first exponentially with a time constant of about 6 msec; it then tends to increase for the next few seconds; finally, it declines slowly with a half-time of about 5 sec. Concomitant with the changes of the outward current, the membrane conductance changes, although virtually no change in electromotive force occurs. Thus, the changes in the membrane conductance represent two phases of K inactivation, one rapidly developing, the other slowly occurring, and a phase of K reactivation, which is interposed between the two inactivations. In isosmotic KCl solution after a conditioning hyperpolarization there occurs an increase in K permeability upon depolarization. When the depolarizations are maintained, the increase of K permeability undergoes changes similar to those observed in the normal medium. The significance of the K inactivation is discussed in relation to the after-potential of the nerve cells.
施加于浸浴在正常溶液中的电压钳制细胞的去极化作用会揭示出一个初始内向电流，随后是一个延迟外向电流。峰值初始电流的最大斜率电导约为漏电导的30倍，但延迟电流的最大斜率电导仅约为漏电导的10倍。在长达30秒的去极化过程中，外向电流不会维持稳定水平，而是首先以约6毫秒的时间常数呈指数下降；然后在接下来的几秒钟内趋于增加；最后，它以约5秒的半衰期缓慢下降。伴随着外向电流的变化，膜电导也发生变化，尽管电动势几乎没有变化。因此，膜电导的变化代表了钾离子失活的两个阶段，一个快速发展，另一个缓慢发生，以及一个钾离子再激活阶段，它介于两次失活之间。在经过预处理超极化后的等渗氯化钾溶液中，去极化时钾离子通透性会增加。当去极化持续时，钾离子通透性的增加会发生类似于在正常介质中观察到的变化。结合神经细胞的后电位讨论了钾离子失活的意义。
