CLUSTER OF VOLTAGE SENSITIVE NA CHANNELS ON AXONS IS INDEPENDENT OF SCHWANN CELL

电压敏感性钠通道在神经元轴突上的分布 营养不良小鼠的背根和腹根 129/ReJ-Lama 2dy用免疫细胞化学法测定。 在这些 神经中有许旺细胞不能增殖的区域 和髓鞘轴突以正常的方式，留下一束束紧密的 包裹着大直径无髓鞘轴突。 我们已经确定了离散的 和钠通道免疫反应性的焦点浓度 共聚焦免疫荧光，免疫电镜和 中压电子显微镜（IVEM），使用 肽衍生的多克隆抗体。 此外，同时 用识别神经元特异性抗人IgG的抗体标记 揭示了一个独特的共定位与钠通道上， 正常和无髓鞘的轴突。 钠斑的存在 通道沿着与它们的锚定蛋白在无髓鞘轴突上， 没有雪旺氏细胞的介入表明轴突可以 独立地形成和维持这些初始聚合。 这 证实雪旺细胞和轴突之间的直接接触不是 需要形成钠通道补丁的节点 尺寸和密度。 此外，这有力地表明， 钠通道从雪旺细胞到轴突的局部转移不是 这一过程所需的。 这项工作发表在Journal of 神经科学（Deerinck等人，神经科学杂志，17：5080-5088，1997）。

The distribution of voltage sensitive sodium channels on axons in the dorsal and ventral spinal roots of the dystrophic mouse 129/ReJ-Lama2dy was determined using immunocytochemistry. In these nerves there are regions in which Schwann cells fail to proliferate and myelinate axons in a normal fashion, leaving bundles of closely packed large diameter amyelinated axons. We have identified discrete and focal concentrations of sodium channel immunoreactivity on these axons by confocal immunofluorescence, immunoelectron microscopy and Intermediate Voltage Electron Microscopy (IVEM) using a peptide-derived polyclonal antibody. In addition, simultaneous labeling with an antibody recognizing neuronal-specific ankyrinG revealed a distinct colocalization with the sodium channels on both normal and amyelinated axons. The presence of patches of sodium channels along with their anchoring protein on amyelinated axons in the absence of intervening Schwann cells demonstrates that axons can independently form and maintain these initial aggregations. This confirms that direct contact between Schwann cell and axon is not required for the formation of sodium channel patches of nodal dimensions and density. Furthermore, this strongly suggests that local transfer of sodium channels from Schwann cells to axons is not required for this process. This work was published in the Journal of Neuroscience (Deerinck et al., J. Neurosci., 17: 5080-5088, 1997).