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Type: Artigo de periódico
Title: Role of Ca2+ in vascular smooth muscle contractions induced by Phoneutria nigriventer spider venom
Author: Teixeira, CE
Corrado, AP
De Nucci, G
Antunes, E
Abstract: Phoneutria nigriventer venom (PNV) contracts vascular tissues and increases arterial blood pressure. This study aimed to investigate the mechanisms involved on PNV-induced contractions of rabbit mesenteric and celiac arteries. Strips of mesenteric and celiac arteries were suspended in a cascade system and superfused with warmed and oxygenated Krebs solution. PNV was dialyzed in order to exclude the participation of biogenic amines in the contractions elicited by the venom. Noradrenaline (NA, 30-300pmol), PNV (1-10 mug), Bay K-8644 (0.3-3nmol) and KCl (10-100mumol) dose-dependently contracted the preparations. Ca2+ -free solution reduced by 38 and 83% the PNV-induced contractions of mesenteric and celiac arteries, respectively. Subsequent infusion of EGTA (0.2 mM) suppressed the residual contractions. Nifedipine (1 muM) and verapamil (10 muM) abolished PNV- and Bay K-8644-evoked contractions, whereas those induced by NA were reduced to a lesser extent. Lanthanum chloride (0.2 mM) inhibited by 75-90% the mesenteric and celiac contractions mediated by PNV. Caffeine (2 mM) fully blocked contractions induced by NA (95% mean inhibition), but only partly reduced those induced by PNV (35% mean inhibition). Ryanodine (10 muM) inhibited by 50% the contractions evoked by NA, but had no effect on the PNV-induced contractions in both tissues. Our findings indicate that PNV contracts vascular smooth muscle mainly due to increased influx of Ca2+ from extracellular sources. (C) 2003 Elsevier Ltd. All rights reserved.
Subject: Phoneutria nigriventer venom
mesenteric artery
celiac artery
Country: Inglaterra
Editor: Pergamon-elsevier Science Ltd
Rights: fechado
Identifier DOI: 10.1016/j.toxicon.2003.10.022
Date Issue: 2004
Appears in Collections:Unicamp - Artigos e Outros Documentos

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