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|Type:||Artigo de periódico|
|Title:||Presynaptic action of Bothriopsis bilineata smargadina (forest viper) venom in vitro|
|Abstract:||In this work, we examined the neuromuscular activity of Bothriopsis bilineata smargadina (forest viper) venom in vertebrate isolated nerve-muscle preparations. In chick biventer cervicis preparations the venom caused concentration-dependent (0.1-30 mu g/ml) neuromuscular blockade that was not reversed by washing, with 50% blockade occurring in 1590 min. Muscle contractures to exogenous acetylcholine and KCl were unaffected by venom, but there was a slight increase in creatine kinase release after 120 min (from 80 +/- 15 to 206 +/- 25 U/ml, n = 6, p < 0.05). In mouse phrenic nerve-diaphragm preparations, the venom (1, 10 and 30 mu g/ml) produced marked facilitation (similar to 120% increase above basal) at the highest concentration followed by neuromuscular blockade: the effects at lower concentrations were considerably less marked. Venom increased the quantal content values after 15 and 30 min followed by significant inhibition at >= 90 min. However, venom did not alter the muscle membrane resting potential or the response to exogenous carbachol. In both preparations, incubation at 22 degrees C instead of 37 degrees C delayed the onset of blockade, as did inhibition of venom PLA2 activity. In curarized mouse preparations, the venom produced only muscle facilitation. These results indicate that B. b. smargadina venom causes neuromuscular blockade in vitro by a presynaptic mechanism involving (C) 2011 Elsevier Ltd. All rights reserved.|
|Subject:||Bothriopsis bilineata smargadina|
|Editor:||Pergamon-elsevier Science Ltd|
|Appears in Collections:||Artigos e Materiais de Revistas Científicas - Unicamp|
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