Offner F F
Biophys J. 1972 Dec;12(12):1583-629. doi: 10.1016/S0006-3495(72)86185-X.
The model of the excitable membrane assumes common channels for Na(+) and K(+); the two ion species interact within the pores through their electrostatic forces. The electric field varies across the membrane and with time, as a result of ionic redistribution. Ionic flow is primarily controlled by energy barriers at the two interfaces and by Ca(++) adsorption at the external interface. When the membrane is polarized, the high electric field at the external interface acting on the membrane fixed charge keeps the effective channel diameter small, so that only dihydrated ions can cross the interface. The higher energy required to partially dehydrate Na(+) accounts for its lower permeability when polarized. Depolarized, the channel entrance can expand, permitting quadrihydrated ions to pass; the large initial Na(+) flow is the result of the large concentration ratio across the interface. The effect at the internal interface is symmetric; Na(+) crosses with greater difficulty when the membrane is depolarized. Na(+) inactivation occurs when the ion distribution within the membrane has assumed its new steady-state value. Calculations based on parameters consistent with physicochemical data agree generally with a wide range of experiments. The model does not obey the two fundamental Hodgkin-Huxley (HH) postulates (independence principle, ion flow proportional to thermodynamic potential). In several instances the model predicts experimental results which are not predicted by the HH equations.
可兴奋膜模型假定钠（Na⁺）和钾（K⁺）共用通道；这两种离子在孔内通过静电力相互作用。由于离子重新分布，电场在膜上随时间变化。离子流主要受两个界面处的能垒以及外部界面处钙离子（Ca²⁺）吸附的控制。当膜极化时，作用于膜固定电荷的外部界面处的高电场使有效通道直径变小，因此只有二水合离子能够穿过该界面。部分脱去Na⁺水合层所需的能量较高，这解释了极化时其渗透率较低的原因。去极化时，通道入口会扩张，允许四水合离子通过；初始较大的Na⁺流是界面两侧较大浓度比的结果。内部界面处的效应是对称的；膜去极化时Na⁺穿过的难度更大。当膜内离子分布达到其新的稳态值时，Na⁺失活发生。基于与物理化学数据一致的参数进行的计算总体上与广泛的实验结果相符。该模型不遵循霍奇金 - 赫胥黎（HH）的两个基本假设（独立性原理、离子流与热力学势成正比）。在一些情况下，该模型预测出了HH方程未预测到的实验结果。
