Please use this identifier to cite or link to this item: http://repositorio.unifesp.br/handle/11600/42997
Title: PHENTHONIUM INDUCES A TRANSIENT INCREASE OF ACETYLCHOLINE EFFLUX FROM MOTOR-NERVE TERMINALS
Authors: Cysneiros, Roberta Monterazzo [UNIFESP]
Lima-Landman, Maria Teresa Riggio de [UNIFESP]
Souccar, Caden [UNIFESP]
Lapa, Antonio José [UNIFESP]
Universidade Federal de São Paulo (UNIFESP)
Keywords: CHOLINERGIC MODULATION
MOTOR NERVE TERMINAL
ACETYLCHOLINE EFFLUX
Issue Date: 1-Jan-1991
Publisher: Assoc Bras Divulg Cientifica
Citation: Brazilian Journal Of Medical And Biological Research. Sao Paulo: Assoc Bras Divulg Cientifica, v. 24, n. 10, p. 1055-1058, 1991.
Abstract: Phenthonium (10-50-mu-M), a quaternary derivative of 1-hyoscyamine, increases the frequency of miniature end-plate potentials (2-5 fold) and blocks the nicotinic receptor-ionic channel in skeletal muscles. When tested on rat diaphragms previously incubated with [H-3]choline, phenthonium (50-mu-M) increased the spontaneous release of radiolabelled acetylcholine (ACh) from 11.6 +/- 6.4 to 110.5 +/- 40.2 x 10(3) dpm/g within 15 min. The effect was transient, declining to 24.6 +/- 14.7 after 50 min. Subsequent electrical stimulation still in the presence of phenthonium increased the efflux to 164.7 +/- 45.3. The fractional release relative to the level before stimulation did not differ from controls. Phenthonium (20-mu-M) did not increase the spontaneous ACh release but doubled the efflux induced by nerve stimulation. The present results, compared to previous electrophysiological findings, indicate that quantal and nonquantal release are increased by phenthonium. They also show that the transient effect is not due to ACh depletion in nerve terminals.
URI: http://repositorio.unifesp.br/11600/42997
ISSN: 0100-879X
Appears in Collections:Artigo

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