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Sympathetic neuromuscular transmission at a varicosity in a syncytium
Author(s) -
Bennett M.R.,
Cheung A.,
Brain K.L.
Publication year - 1998
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/(sici)1097-0029(19980915)42:6<433::aid-jemt6>3.0.co;2-n
Subject(s) - synaptotagmin 1 , exocytosis , neurotransmission , stx1a , biology , synaptic vesicle , chemistry , neuroscience , secretion , anatomy , microbiology and biotechnology , vesicle , endocrinology , receptor , syntaxin , biochemistry , membrane
Abstract The autonomic neuromuscular junction at a varicosity in the vas deferens is defined by the localization of the vesicle‐associated protein syntaxin in high concentrations in the axolemma and a high density of P2x 1 receptors in a cluster beneath the varicosity. Calcium fluxes have been observed in all individual varicosities of a nerve terminal on the arrival of an impulse even though recordings made from these varicosities of the electrical signs of transmission with loose‐patch electrodes over the varicosities show that they have very different probabilities for the secretion of a quantum. The fact that some varicosities seldom release a quantum on the arrival of an impulse is supported by the observation that antibodies against the N‐terminus of synaptotagmin, which uniquely label the inside of synaptic vesicles when they undergo exocytosis, fail to do so in some varicosities during nerve stimulation whereas they do in others. It is suggested that the probability for secretion from a varicosity depends on the number of secretosomes that the varicosity possesses, where a secretosome is a complex of syntaxin, synaptotagmin, an N‐type calcium channel, and a synaptic vesicle. Microsc. Res. Tech. 42:433–450, 1998. © 1998 Wiley‐Liss, Inc.