FLUORESCENTLY LABELED NA+ CHANNELS ARE LOCALIZED AND IMMOBILIZED TO SYNAPSES OF INNERVATED MUSCLE-FIBERS
FLUORESCENTLY LABELED NA+ CHANNELS ARE LOCALIZED AND IMMOBILIZED TO SYNAPSES OF INNERVATED MUSCLE-FIBERS
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DOI：
10.1038/321063a0
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发表时间：
1986-05-01
期刊：
影响因子：
64.8
通讯作者：
ANGELIDES, KJ
中科院分区：
文献类型：
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作者：
ANGELIDES, KJ
分离的电压依赖性钠离子通道的运动神经元的小丘和节点的Ranvier在有髓轴突是至关重要的神经冲动的传导1，2。然而，对肌肉纤维上电压依赖性Na+通道的分布知之甚少。最近Beamet等研究表明，Na+通道主要集中在神经肌肉接头附近。为了确定电压依赖性Na+通道在肌肉上的分布的拓扑结构和机制，现在已经使用显微荧光测定法和荧光光漂白恢复（FPR）来测量荧光标记的Na+通道在无神经支配和有神经支配的肌纤维上的密度和侧向流动性。在无神经支配的肌管上，Na+通道弥散分布且自由移动的，而在神经支配后，通道集中在神经元接触部位。这些通道是固定的，并与乙酰胆碱受体（AChR）共定位。在连接外区域，Na+通道密度较低，并且通道更移动的。结果表明，神经诱导Na+通道重新分布，迁移和共定位与AChRs在网站的神经元接触。
Segregation of voltage-dependent sodium channels to the hillock of motoneurones and nodes of Ranvier in myelinated axons is crucial for conduction of the nerve impulse1,2. Much less is known, however, about the distribution of voltage-dependent Na+channels on muscle fibres. Recently, Beamet al.3have shown that Na+channels are concentrated near the neuromuscular junction. To determine the topography and mechanisms governing the distribution of voltage-dependent Na+channels on muscle, microfluorimetry and fluorescence photobleach recovery (FPR) have now been used to measure the density and lateral mobility of fluorescently labelled Na+channels on uninnervated and innervated muscle fibres. On uninnervated myotubes, Na+channels are diffusely distributed and freely mobile, whereas after innervation the channels concentrate at neuronal contact sites. These channels are immobile and co-localize with acetylcholine receptors (AChRs). At extrajunctional regions the Na+channel density is lower and the channels more mobile. The results suggest that the nerve induces Na+channels to redistribute, immobilize and co-localize with AChRs at sites of neuronal contact.