Marom S, Abbott L F
Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02254.
Biophys J. 1994 Aug;67(2):515-20. doi: 10.1016/S0006-3495(94)80518-1.
Inactivation of many ion channels occurs through largely voltage-independent transitions to an inactivated state from the open state or from other states in the pathway leading to opening of the channel. Because this form of inactivation is state-dependent rather than voltage-dependent, it cannot be described by the standard Hodgkin-Huxley formalism used in virtually all modeling studies of neuronal behavior. Using two examples, cumulative inactivation of the Kv3 potassium channel and inactivation of the fast sodium channel, we extend the standard formalism for modeling macroscopic membrane currents to account for state-dependent inactivation. Our results provide an accurate description of cumulative inactivation of the Kv3 channel, new insight into inactivation of the sodium channel, and a general framework for modeling macroscopic currents when state-dependent processes are involved. In a model neuron, the macroscopic Kv3 current produces a novel short-term memory effect and firing delays similar to those seen in hippocampal neurons.
许多离子通道的失活主要通过与电压无关的转变，从开放状态或通向通道开放的途径中的其他状态转变为失活状态。由于这种失活形式是状态依赖性的而非电压依赖性的，所以它无法用几乎所有神经元行为建模研究中使用的标准霍奇金-赫胥黎形式体系来描述。通过两个例子，即Kv3钾通道的累积失活和快速钠通道的失活，我们扩展了用于对宏观膜电流进行建模的标准形式体系，以考虑状态依赖性失活。我们的结果准确描述了Kv3通道的累积失活，为钠通道的失活提供了新的见解，并且为涉及状态依赖性过程时的宏观电流建模提供了一个通用框架。在一个模型神经元中，宏观Kv3电流产生了一种新颖的短期记忆效应和类似于海马神经元中所见的放电延迟。
