荷兰皇家艺术与科学学院Maarten H.P. Kole研究组发现沿髓鞘轴突的跳跃传导含有轴突周的纳米回路。相关论文于2019年12月26日在线发表于《细胞》杂志。

研究人员结合电子显微镜和受实验约束的电缆模型，制作了膜片钳和高速电压校准过的、有髓的新皮质锥体轴突的跨节和节间腋窝电势的光学记录。研究结果揭示了纳米级但导电的轴突周围空间，在节旁处未完全密封，从而将低电容髓鞘和节间性轴突之间的电位分开。

新兴的双电缆模型再现了跨节点和跨节点的电压波形的记录演化，包括在节点间的轴突中的衰减波之前传播的快速节点电位，从而揭示了跨时空跳跃的机制。

据了解，髓鞘在很大程度上加速了电脉冲沿轴突的传播，并在节点之间（从Ranvier的一个节点到另一个节点）跨节点产生了“跳跃”的动作电位。然而，背后的电路以及亚髓磷脂传导在跳跃传导中的存在和作用仍然难以捉摸。

附：英文原文

Title: Saltatory Conduction along Myelinated Axons Involves a Periaxonal Nanocircuit

Author: Charles C.H. Cohen, Marko A. Popovic, Jan Klooster, Marie-Theres Weil, Wiebke Mbius, Klaus-Armin Nave, Maarten H.P. Kole

Issue&Volume: December 26, 2019

Abstract: The propagation of electrical impulses along axons is highly accelerated by the myelin sheath and produces saltating or “jumping” action potentials across internodes, from one node of Ranvier to the next. The underlying electrical circuit, as well as the existence and role of submyelin conduction in saltatory conduction remain, however, elusive. Here, we made patch-clamp and high-speed voltage-calibrated optical recordings of potentials across the nodal and internodal axolemma of myelinated neocortical pyramidal axons combined with electron microscopy and experimentally constrained cable modeling. Our results reveal a nanoscale yet conductive periaxonal space, incompletely sealed at the paranodes, which separates the potentials across the low-capacitance myelin sheath and internodal axolemma. The emerging double-cable model reproduces the recorded evolution of voltage waveforms across nodes and internodes, including rapid nodal potentials traveling in advance of attenuated waves in the internodal axolemma, revealing a mechanism for saltation across time and space.

DOI: 10.1016/j.cell.2019.11.039

Source: https://www.cell.com/cell/fulltext/S0092-8674(19)31324-8