Efeitos da peçonha de Bothrops neuwiedi pauloensis sobre preparações neuromusculares de ave e mamifero : aspectos miograficos e eletrofisiologicos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

In the present study, the phannacological effects of Bothrops neuwiedi pauloensis venom were studied in mouse phrenic nerve-diaphragm and chick biventer cervicis preparations. In chick preparations, venom (1, 5, 10,50 and 100 J.1g1ml) produoed progressive, concentration-dependent neuromuscular blockade. At low venom concentrations (1, 5, 10 and 20 J.1g1m1) , the responses to exogenously applied KCI (13.4 mM) were inhibited whereas those to acetylcholine (ACh, 110 mM alone or cumulative concentrations of 10-6-10-2 M) were unaffected. At high venom concentrations (50 and 100 J.1g1ml) , there was pronounoed muscle contracture with inhibition of the responses to ACh, KCI and direct stimulation. These activities were not observed at 20-24°C compareci to 37°C. At 20 J.1g1m1, the venom irreversibly inhibited indirectly evoked twitches in mouse phrenic nerve-diaphragm preparations (60 ::t 10% inhibition, mean ::t SEM; p<0.05; n = 6). At 50 J.1g1m1, the venom blocked indirectly (n = 5) and directly (n=6) evoked twitches in mouse hernidiaphragms. When Ca2+ (1.8 mM) was replaced by S~ (4 mM), the venom (50 J.1g/ml) produoed only partial blockade (40.3:t 7.8% inhibition; p<0.05; n = 3) after 120 mino The venom (20 J.1g1m1) inaeased the number of miniature end-plate potentials by a maximum of 562::t 3%, (p<0.05) after 120 min, and also increased the frequency of giant miniature end-plate potentials (25 ::t 2%, 1><0.05) in 9 out of 10 end-plates -41.3:t 3.6 mV (24 fibers; p

ASSUNTO(S)

eletrofisiologia cobra venenosa - veneno junção neuromuscular veneno - efeito fisiologico

ACESSO AO ARTIGO

Documentos Relacionados