Role of non-quantum acetylcholine secretion in neural control of the membrane potential in skeletal muscle fibers of rats

Autor: S. T. Magsumov, A. Kh. Urazaev, Poletaev Gi
Rok vydání: 1996
Předmět:
Zdroj: Neurophysiology. 27:54-57
ISSN: 1573-9007
0090-2977
DOI: 10.1007/bf01054568
Popis: Experiments on muscle fibers of the rat diaphragm (in vitro denervation) showed that their three-hour incubation in the cultural medium results in an 8-mV drop in the resting membrane potential (RMP). Addition of 5·10−8 M carbacholine to the cultural medium, mimicing the effect of non-quantum acetylcholine, delayed depolarization of the denervated muscle. The effect of carbacholine could not be eliminated byd-tubocurarine (5·10−6 M), a postsynaptic acetylcholine receptor blocker, and by ouabain (1·10−4 M), and inhibitor of Na+, K+-ATPase of the membrane. At the same time, the effect could be completely eliminated by Mg2+ ions (5·10−3 M), which blocked Ca2+ channels of the membrane, by N-nitroarginine (1·10−4 M), which inhibited the enzyme NO-synthase, and by hemoglobin (2·10−5 M), which inactivated the extracellular NO molecules. It is concluded that the released non-quantum acetylcholine can contribute to neural control of RMP of cross-striated muscle fibers via the Ca2+-dependent activation of NO synthesis in the sarcoplasm. The NO molecules can play the role of a retrograde signal indicative of the normal functioning of the neuromuscular synapse. The impairment of this link caused by a denervation-induced cessation of the non-quantum secretion can serve as a signal triggering the early changes in the muscle membrane following nerve transection.
Databáze: OpenAIRE
Externí odkaz: