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Type: Artigo de periódico
Title: Pharmacological Study Of A New Asp49 Phospholipase A(2) (bbil-tx) Isolated From Bothriopsis Bilineata Smargadina (forest Viper) Venom In Vertebrate Neuromuscular Preparations.
Author: Floriano, Rafael Stuani
Carregari, Victor Corasolla
de Abreu, Valdemir Aparecido
Kenzo-Kagawa, Bruno
Ponce-Soto, Luis Alberto
da Cruz-Höfling, Maria Alice
Hyslop, Stephen
Marangoni, Sergio
Rodrigues-Simioni, Léa
Abstract: The neuromuscular activity of Bbil-TX, a PLA2 with catalytic activity isolated from Bothriopsis bilineata smargadina venom, was examined in chick biventer cervicis (BC) and mouse phrenic nerve-diaphragm (PND) preparations. In BC preparations, Bbil-TX (0.5-10 μg/ml) caused time- and concentration-dependent blockade that was not reversed by washing; the times for 50% blockade were 87 ± 7, 41 ± 7 and 19 ± 2 min (mean ± SEM; n = 4-6) for 1, 5 and 10 μg/ml, respectively. Muscle contractures to exogenous ACh and KCl were unaffected. The toxin (10 μg/ml) also did not affect the twitch-tension of directly-stimulated, curarized (10 μg/ml) BC preparations. However, Bbil-TX (10 μg/ml) produced mild morphological alterations (edematous and/or hyperchromic fibers) in BC; there was also a progressive release of CK (from 116 ± 17 IU/ml (basal) to 710 ± 91 IU/ml after 45 min). Bbil-TX (5 μg/ml)-induced blockade was markedly inhibited at 22-24 °C and pretreatment with p-bromophenacyl bromide (p-BPB) abolished the neuromuscular blockade. Bbil-TX (3-30 μg/ml, n = 4-6) caused partial time- and concentration-dependent blockade in PND preparations (52 ± 2% at the highest concentration). Bbil-TX (30 μg/ml) also markedly reduced the MEPPs frequency [from 26 ± 2.5 (basal) to 10 ± 1 after 60 min; n = 5; p < 0.05] and the quantal content [from 94 ± 14 (basal) to 24 ± 3 after 60 min; n = 5; p < 0.05] of PND preparations, but caused only minor depolarization of the membrane resting potential [from -80 ± 1 mV (basal) to -66 ± 2 mV after 120 min; n = 5; p < 0.05], with no significant change in the depolarizing response to exogenous carbachol. These results show that Bbil-TX is a presynaptic PLA2 that contributes to the neuromuscular blockade caused by B. b. smargadina venom.
Subject: Acetophenones
Miniature Postsynaptic Potentials
Muscle Contraction
Muscle, Skeletal
Neuromuscular Blockade
Neuromuscular Junction
Phospholipases A2, Secretory
Phrenic Nerve
Reptilian Proteins
Viper Venoms
Citation: Toxicon : Official Journal Of The International Society On Toxinology. v. 69, p. 191-9, 2013-Jul.
Rights: fechado
Identifier DOI: 10.1016/j.toxicon.2013.03.006
Date Issue: 2013
Appears in Collections:Unicamp - Artigos e Outros Documentos

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