Zeng Shangyou, Jung Peter
Department of Physics, Xiangtan University, Hunan Province, 411105, People's Republic of China.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Dec;78(6 Pt 1):061916. doi: 10.1103/PhysRevE.78.061916. Epub 2008 Dec 17.
Although most sodium ion channels clustered in nodes of Ranvier provide the physiological basis for saltatory conduction, sodium ion channels cannot be excluded from internodal regions completely. The density of internodal sodium ion channels is of the order of 10/microm2. The function of internodal sodium ion channels has been neglected for a long time; however, experimental and theoretical results show that internodal sodium ion channels play an important role in action potential propagation. In this paper, based on the compartment model, we investigate the function of internodal sodium ion channels. We find that internodal sodium ion channels can promote action potential propagation, enlarge the maximal internodal distance guaranteeing stable action potential propagation, and increase the propagation speed of action potentials. In this paper, we find an optimal conductance of internodal sodium ion channels (4-5 mS/cm2), which accords with the active internodal sodium ion conductance in a real myelinated axon. With the optimal conductance, the average sodium ion channel conductance of the axon is minimal, and the metabolic energy consumption due to ion channels is also minimal.
尽管大多数聚集在郎飞结处的钠离子通道为跳跃式传导提供了生理基础，但钠离子通道也不能完全排除在结间区域之外。结间钠离子通道的密度约为10/μm²。长期以来，结间钠离子通道的功能一直被忽视；然而，实验和理论结果表明，结间钠离子通道在动作电位的传播中起着重要作用。在本文中，基于房室模型，我们研究了结间钠离子通道的功能。我们发现，结间钠离子通道可以促进动作电位的传播，扩大保证动作电位稳定传播的最大结间距离，并提高动作电位的传播速度。在本文中，我们发现结间钠离子通道的最佳电导率（4-5 mS/cm²），这与真实有髓轴突中的活性结间钠离子电导率一致。在最佳电导率下，轴突的平均钠离子通道电导率最小，并且由于离子通道引起的代谢能量消耗也最小。
