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Type: Artigo de periódico
Title: Toxin 2 (PhTx2), a neurotoxic fraction from Phoneutria nigriventer spider venom, causes acute morphological changes in mouse skeletal muscle
Author: Mattiello-Sverzuta, AC
da Cruz-Hofling, MA
Abstract: Phoneutria nigriventer (Labidognatha, Ctenidae) is a spider found in the warm regions of South America. Bites by this species cause intense local pain, autonomic dysfunction and paralysis. PhTx2, a neurotoxic fraction of the venom of this species, interferes with the physiology of sodium channel function. The present study describes the morphological changes in mouse phrenic nerve and diaphragm muscle after 15, 30, 45 and 60 min of incubation with 1 mu g Of PhTx2/mL. Light and transmission electron microscopy showed that PhTx2 caused progressive myonecrosis which involved swelling of the sarcoplasmic reticulum, mitochondrial damage, disorganization of the sarcomeres, zones of hypercontracted myofibrils and rupture of the plasma membrane. The intramuscular fascicles of the phrenic nerve showed vacuolated myelinated axons and Schwann cells. The neuromuscular junctions had vesicle-depleted nerve terminals with swollen mitochondria. The axolemma was frequently invaginated and sequestered portions of the axoplasm, or was sometimes interrupted at the site of the synaptic gutter. The post-synaptic junctional folds were shallow and disperse. These morphological alterations in the muscle and nerve fibres were similar to those caused by osmotic disturbances and agree with the ability of PhTx2 to increase the permeability of sodium channels. An increase in sodium influx would probably be accompanied by an influx of water and an elevation in the concentration of cytosolic calcium as a result of calcium release by the sarcoplasmic reticulum and.;or mitochondria and the entry of extracellular calcium. The morphological effects caused bq PhTx2 were comparable to those seen with Phoneutria nigriventer whole venom which is known to activate and to delay the inactivation of sodium channels. We conclude that PhTx2, is probably the main toxic fraction responsible for such morphological alterations. (C) 2000 Elsevier Science Ltd. All rights reserved.
Subject: PhTx2
Phoneutria nigriventer venom
skeletal muscle
Country: Inglaterra
Editor: Pergamon-elsevier Science Ltd
Citation: Toxicon. Pergamon-elsevier Science Ltd, v. 38, n. 6, n. 793, n. 812, 2000.
Rights: fechado
Identifier DOI: 10.1016/S0041-0101(99)00188-9
Date Issue: 2000
Appears in Collections:Unicamp - Artigos e Outros Documentos

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