期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1987
卷号：84
期号：8
页码：2550-2554
DOI：10.1073/pnas.84.8.2550
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：It has been proposed that acetylcholine receptor channels exhibit a functionally distinct "junctional" form at the region of synaptic contact between nerve and muscle. As a direct test of this idea, we compared acetylcholine-activated single-channel currents from the synaptic membrane to those obtained from nonsynaptic sites on freshly dissociated adult mouse toe muscle. We observed, at locations along the entire length of the cell, openings by a channel with a high conductance (70 pS) and brief open time (approximately 2 msec), characteristic of the classical "junctional type" of acetylcholine receptor. In 8 out of 10 synaptic and in 9 out of 19 nonsynaptic recordings, we also observed infrequent openings by a low-conductance (45-pS) channel traditionally associated only with nonsynaptic regions. In these recordings the low-conductance acetylcholine receptor channel averaged only 3% of the total channel openings. Comparisons of synaptic and nonsynaptic patches indicated no trend toward an increased proportion of low-conductance channel openings with increased distance from the synapse. These findings support the view that the functional properties of the acetylcholine receptor channel do not depend on proximity to the synapse in innervated mouse skeletal muscle.
