Attwell D, Eisner D
Biophys J. 1978 Dec;24(3):869-75. doi: 10.1016/S0006-3495(78)85426-5.
Each gating mechanism controlling permeability in a membrane may be influenced by only a few charge binding sites on the membrane surface, so that fluctuations in the occupancy of these sites are important. Tow extreme cases arise. (a) The time scale of these fluctuations is much shorter than the gating time constant. Then the gating mechanisms are subject to a rapidly varying electric field. If the gating in the absence of these fluctuations obeys exponential kinetics, so does the gating in the presence of the fluctuations. Changes in surface charge do not simply shift the gating variable curves on the voltage axis, but also change their shape. Such effects are seen experimentally and cannot be explained in terms of conventional surface charge theory. If the activation curve in the absence of any surface charge binding is symmetric about the half-activation point, when some of the surface charge sites are occupied the activation curve is in general asymmetric. (b) The fluctuations occur much more slowly than the gating reaction. There are several pools of channels present with different time constant and activation curves. Again the activation curve is asymmetric about the half-activation point, and its shape is changed by alterations in the surface charge. The kinetics of gating of the whole population of channels are multiexponential.
控制细胞膜通透性的每种门控机制可能仅受膜表面少数几个电荷结合位点的影响，因此这些位点占据情况的波动很重要。会出现两种极端情况。(a) 这些波动的时间尺度远短于门控时间常数。此时门控机制会受到快速变化的电场影响。如果在没有这些波动的情况下门控遵循指数动力学，那么在有波动的情况下门控也是如此。表面电荷的变化不仅会使门控变量曲线在电压轴上发生位移，还会改变其形状。这种效应在实验中可以观察到，并且无法用传统的表面电荷理论来解释。如果在没有任何表面电荷结合的情况下激活曲线关于半激活点对称，那么当一些表面电荷位点被占据时，激活曲线通常会不对称。(b) 波动发生的速度比门控反应慢得多。存在几个具有不同时间常数和激活曲线的通道池。激活曲线同样关于半激活点不对称，并且其形状会因表面电荷的改变而变化。整个通道群体的门控动力学是多指数的。
