异常钾通道门控速率与钙和钾离子浓度的函数关系。
Anomalous potassium channel-gating rates as functions of calcium and potassium ion concentrations.
作者信息
Fohlmeister J F, Adelman W J
出版信息
Biophys J. 1982 Feb;37(2):427-31. doi: 10.1016/S0006-3495(82)84688-2.
With near normal monovalent ionic concentrations, the rate of increase of the potassium conductance after a depolarizing voltage-clamp step is slowed when the external calcium concentration is increased. This trend in the rise-time with changes in calcium is reversed when the axointernal potassium concentration is reduced (150 mM) and the periaxonal concentration is increased (50 mM); that is, the rise-time decrease with increasing calcium concentration. Furthermore, the degree of sigmoidality of the K-conductance time-course always increase when the rise-times increase for a given test potential. In the case of calcium surface-charge screening, these effects may be caused by a shifted distribution of K-ions within the channels following the altered ion gradient, and by a consequent shift in the reciprocal electrostatic interactions between the ionic charges and channel-gate charges.
在单价离子浓度接近正常时，当外部钙浓度增加时，去极化电压钳制步骤后钾电导的增加速率会减慢。当轴突内钾浓度降低（150 mM）且轴突周围浓度增加（50 mM）时，这种钙变化时上升时间的趋势会逆转；也就是说，上升时间会随着钙浓度的增加而减少。此外，对于给定的测试电位，当上升时间增加时，钾电导时间进程的S形程度总是会增加。在钙表面电荷筛选的情况下，这些效应可能是由于离子梯度改变后通道内钾离子分布的改变，以及离子电荷与通道门电荷之间相互静电相互作用的相应改变所致。
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