Goychuk Igor, Hänggi Peter
Institute of Physics, University of Augsburg, Universitätsstrasse 1, D-86135 Augsburg, Germany.
Proc Natl Acad Sci U S A. 2002 Mar 19;99(6):3552-6. doi: 10.1073/pnas.052015699. Epub 2002 Mar 12.
The opening rate of voltage-gated potassium ion channels exhibits a characteristic knee-like turnover where the common exponential voltage dependence changes suddenly into a linear one. An explanation of this puzzling crossover is put forward in terms of a stochastic first passage time analysis. The theory predicts that the exponential voltage dependence correlates with the exponential distribution of closed residence times. This feature occurs at large negative voltages when the channel is predominantly closed. In contrast, the linear part of voltage dependence emerges together with a nonexponential distribution of closed dwelling times with increasing voltage, yielding a large opening rate. Depending on the parameter set, the closed-time distribution displays a power law behavior that extends over several decades.
电压门控钾离子通道的开放速率呈现出一种特征性的膝状转变，即常见的指数电压依赖性突然转变为线性电压依赖性。基于随机首次通过时间分析，对这种令人费解的转变提出了一种解释。该理论预测，指数电压依赖性与关闭停留时间的指数分布相关。当通道主要处于关闭状态时，这种特征出现在大的负电压下。相反，随着电压升高，电压依赖性的线性部分与关闭停留时间的非指数分布一起出现，从而产生较高的开放速率。根据参数设置，关闭时间分布呈现出跨越几十年的幂律行为。
