Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/194633
Type: Artigo de periódico
Title: Nature Of The Postsynaptic Action Of Crotoxin At Guinea-pig Diaphragm End-plates.
Author: Brazil, O V
Fontana, M D
Heluany, N F
Abstract: Crotoxin is known to desensitize the nicotinic receptor of Torpedo marmorata and Electrophorus electricus electroplaques. The aim of the present study was to elucidate whether the postsynaptic effect of crotoxin at a mammalian muscle end-plate is also caused by receptor desensitization or results from a curaremimetic action. For this purpose, we investigated the action of 4-aminopyridine (4-AP) on crotoxin-induced blockade of miniature end-plate potentials (m.e.p.p.s) and of the depolarization of end-plates produced by carbachol. The experiments were carried out in guinea-pig diaphragms bathed in Tyrode solution at 37 degrees C and gassed with 95% O2, 5% CO2. The potentials were measured with conventional techniques using glass microelectrodes. Even at low concentrations, crotoxin blocked the m.e.p.p.s and this blockade was antagonized by 4-AP. Neostigmine was without effect. 4-AP did not restore the m.e.p.p.s blocked by either d-tubocurarine (dTc) or beta-bungarotoxin (beta-BTX). 4-AP also antagonized the crotoxin-induced blockade of the end-plate depolarization produced by carbachol. These results show that the postsynaptic effect of crotoxin at the guinea-pig muscle end-plate also results from nicotinic receptor desensitization.
Subject: 4-aminopyridine
Animals
Carbachol
Crotoxin
Diaphragm
Dose-response Relationship, Drug
Electrophysiology
Guinea Pigs
Muscle, Smooth
Synaptic Transmission
Rights: fechado
Identifier DOI: 
Address: http://www.ncbi.nlm.nih.gov/pubmed/10701179
Date Issue: 2000
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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