Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/195367
Type: Artigo de periódico
Title: Neurotoxic And Myotoxic Actions Of Naja Naja Kaouthia Venom On Skeletal Muscle In Vitro.
Author: Reali, Marielga
Serafim, Francine G
da Cruz-Höfling, Maria Alice
Fontana, Marcos D
Abstract: The neuromuscular and skeletal muscle actions of Naja naja kaouthia snake venom were studied in mammalian (rat left hemidiaphragm) and avian (chick biventer cervicis) nerve-muscle preparations. The venom (5 and 10 micro g/ml) produced neuromuscular blockade (85% in 36.8+/-2.0min, mean+/-SEM, n=5, and 18+/-0.6min, n=3, p<0.01, respectively) in the rat preparation. That the phospholipase A(2) (PLA(2)) activity of the venom is involved in this effect was evaluated by inhibiting this enzyme with p-bromophenacyl bromide. This resulted in significantly (p<0.01) increasing the time required for 85% blockade with 5 and 10 micro g/ml to 54+/-4.6min (n=3) and 29+/-0.6min (n=3), respectively. In chick preparations, the venom (5 micro g/ml) produced neuromuscular blockade in 14.0+/-1.8min (n=5). The contractures to exogenous acetylcholine were completely inhibited by the venom, whereas those to 134 micro M KCl were partially blocked in chick preparations (n=4, n=3, respectively). The venom (5 micro g/ml) produced a progressive decrease in the amplitude of miniature end-plate potentials (m.e.p.ps) in the rat hemidiaphragm, but did not alter the resting membrane potential at 5 micro g/ml. Neostigmine (5.8 micro M) immediate and partially reversed the 85% blockade produced by venom (61%, n=3) in rat preparations, as did 4-aminopyridine (53 micro M) ( approximately 59%, n=3). The 4-aminopyridine and neostigmine also restored the m.e.p.ps to pre-venom (control) values. In rat preparations, the venom damaged 47%+/-11% and 62.7+/-3.6% of the muscle fibers at concentrations of 5 and 10 micro g/ml, respectively. For venom in which PLA(2) activity was inhibited, the corresponding values were 38+/-11.8% (5 micro g/ml) and 67+/-9.6% (10 micro g/ml). These findings suggest a post-synaptic neurotoxic action for N. n. kaouthia venom, and that inhibiting phospholipase activity of the venom reduces significantly the neuromuscular block but not the direct myotoxicity.
Subject: Animals
Chickens
Cobra Venoms
Diaphragm
Elapidae
In Vitro Techniques
Muscle Contraction
Muscle, Skeletal
Necrosis
Phospholipases A
Phrenic Nerve
Rats
Citation: Toxicon : Official Journal Of The International Society On Toxinology. v. 41, n. 6, p. 657-65, 2003-May.
Rights: fechado
Address: http://www.ncbi.nlm.nih.gov/pubmed/12727270
Date Issue: 2003
Appears in Collections:Unicamp - Artigos e Outros Documentos

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