Matzner O, Devor M
Department of Cell and Animal Biology, Hebrew University of Jerusalem, Israel.
Brain Res. 1992 Nov 27;597(1):92-8. doi: 10.1016/0006-8993(92)91509-d.
The Hodgkin-Huxley equation for electrogenesis in the voltage clamped squid giant axon was used to predict the effect of altering maximal Na+ conductance (gNa+max) on the repetitive firing process. The main finding was that increasing gNa+max, without changing any other membrane parameter, reduced the threshold current required to evoke repetitive firing. That is, it rendered the membrane hyperexcitable. Threshold for evoking single action potentials was also affected, but much less so. Other consequences of increasing gNa+max were a decrease in the minimum sustainable rhythmic firing frequency (mRFF), a monotonic increase in firing frequency at any given suprathreshold stimulus intensity, an increase in the current value at which intense depolarizing stimuli block rhythmogenesis, an increase in the maximal sustainable firing frequency using intense currents (MRFF), and the consequent expansion of the dynamic range for stimulus encoding. Thus, the control of gNa+max through the regulation of Na+ channel synthesis and membrane incorporation at sites of rhythmogenesis (e.g. axon hillock-initial segment region, or peripheral sensory endings) is a potential regulatory mechanism for neuronal excitability and stimulus encoding.
霍奇金-赫胥黎方程用于描述电压钳制枪乌贼巨轴突中的电产生过程，该方程被用来预测改变最大钠离子电导（gNa+max）对重复放电过程的影响。主要发现是，在不改变任何其他膜参数的情况下增加gNa+max，会降低引发重复放电所需的阈值电流。也就是说，它使膜变得过度兴奋。引发单个动作电位的阈值也受到影响，但影响较小。增加gNa+max的其他后果包括最小可持续节律性放电频率（mRFF）降低、在任何给定的阈上刺激强度下放电频率单调增加、强烈去极化刺激阻断节律发生时的电流值增加、使用强电流时最大可持续放电频率（MRFF）增加，以及随之而来的刺激编码动态范围扩大。因此，通过调节钠离子通道合成以及在节律发生部位（如轴丘-起始段区域或外周感觉末梢）的膜整合来控制gNa+max，是一种调节神经元兴奋性和刺激编码的潜在机制。
