Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/194228
Type: Artigo de periódico
Title: An Unusual Presynaptic Action Of Bothrops Insularis Snake Venom Mediated By Phospholipase A2 Fraction.
Author: Cogo, J C
Prado-Franceschi, J
Giglio, J R
Corrado, A P
Cruz-Höfling, M A
Donato, J L
Leite, G B
Rodrigues-Simioni, L
Abstract: A phospholipase A2-containing fraction was isolated from the venom of Bothrops insularis by a combination of gel filtration on Sephadex G-150 and ion exchange chromatography on DEAE-Sephadex. Peak IV of the latter chromatography containing all of the phospholipase A2 (PLA2) activity, was assayed on isolated neuromuscular preparations. In the mouse phrenic nerve-diaphragm incubated in Tyrode at 37 degrees C, the PLA2 fraction produced an initial increase in the twitch tension and in the frequency of the mepps, followed by a dose-dependent, irreversible blockade. The replacement of 1.8 mM Ca2+ by 4 mM Sr2 inhibited the neuromuscular blocking effect of the fraction. In the chick hiventer cervicis preparation incubated with Krebs solution at 37 degrees C, the PLA2 fraction induced blockade but did not affect the response to acetylcholine and K+, excluding the involvement of post-synaptic and direct muscular effects. A low temperature (18-22 degrees C) incubation prevented the neuromuscular effect from developing. These results suggest that the PLA2-containing fraction acts predominantly at presynaptic sites at the neuromuscular junction. This fraction also accounts for most of the pharmacological effects of the crude venom.
Subject: Animals
Bothrops
Chickens
Chromatography, Gel
Chromatography, Ion Exchange
Crotalid Venoms
Diaphragm
Dose-response Relationship, Drug
In Vitro Techniques
Male
Membrane Potentials
Mice
Neuromuscular Blockade
Neuromuscular Blocking Agents
Neuromuscular Junction
Phospholipases A
Phospholipases A2
Phrenic Nerve
Presynaptic Terminals
Time Factors
Rights: fechado
Identifier DOI: 
Address: http://www.ncbi.nlm.nih.gov/pubmed/9723831
Date Issue: 1998
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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