Vabnick I, Shrager P
Department of Biochemistry and Biophysics, University of Rochester Medical Center, New York 14642, USA.
J Neurobiol. 1998 Oct;37(1):80-96.
The development of myelinated axons represents one of the most complex interactions among different cell types in the nervous system. Striking changes occur in both morphology and function in the early postnatal period. Myelination effectively isolates electrically most of the axolemma and dramatically alters the pathways for current flow that are required for rapid, reliable, and efficient conduction. Correspondingly, ion channels must be directed to and stabilized at their required sites. In the case of Na+ channels, this requires a 25-fold increase in density within nodes of Ranvier, and, in mammalian fibers, a virtually complete spatial separation from voltage-dependent K+ channels. Nodes must also be properly spaced to ensure a high conduction velocity and energy efficiency without compromising the safety factor for reliable propagation. In this review, we consider the events responsible for axon development, emphasizing the involvement of ion channels. We discuss the current state of research in this area, including some controversies regarding mechanisms of neuron-glial communication.
有髓轴突的发育代表了神经系统中不同细胞类型之间最复杂的相互作用之一。在出生后的早期阶段，形态和功能都会发生显著变化。髓鞘形成有效地隔离了大部分轴膜的电活动，并极大地改变了快速、可靠和高效传导所需的电流通路。相应地，离子通道必须被引导到其所需位置并在那里稳定下来。就钠通道而言，这需要在郎飞结内密度增加25倍，并且在哺乳动物纤维中，与电压依赖性钾通道几乎完全在空间上分离。节点也必须有适当的间距，以确保高传导速度和能量效率，同时不损害可靠传播的安全系数。在这篇综述中，我们考虑了负责轴突发育的事件，重点强调了离子通道的参与。我们讨论了该领域的研究现状，包括一些关于神经元-胶质细胞通讯机制的争议。
