Received: May 28, 2003, Accepted: August 11, 2003, Published online: February 11, 2005.

NEUROMUSCULAR ACTIVITY OF Bothrops neuwiedi pauloensis SNAKE VENOM IN MOUSE NERVE-MUSCLE PREPARATIONS

DURIGON A. M. (1), BORJA-OLIVEIRA C. R. (1), DAL BELO C. A. (1), OSHIMA-FRANCO Y. (1)., COGO J. C. (2), LAPA A. J. (3), SOUCCAR C. (3), RODRIGUES-SIMIONI L. (1)

(1) Departamento de Farmacologia, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP),  Campinas, SP, Brasil; (2) Instituto de Pesquisa e Desenvolvimento (IP&D), Universidade do Vale do Paraíba (UNIVAP), São José dos Campos, SP, Brasil; (3) Departamento de Farmacologia, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, SP, Brasil

ABSTRACT: The pharmacological effects of Bothrops neuwiedi pauloensis venom on mouse phrenic nerve-diaphragm (PND) preparations were studied. Venom (20 g/ml) irreversibly inhibited indirectly evoked twitches in PND preparations (60 10% inhibition, mean SEM; p<0.05; n=6). At 50 g/ml, the venom blocked indirectly and directly (curarized preparations) evoked twitches in mouse hemidiaphragms. In the absence of Ca2+, venom (50 g/ml), produced partial blockade only after an 80 min incubation, which reached 40.3 7.8% (p<0.05; n=3) after 120 min. Venom (20 g/ml) increased (25 2%, p0.05) the frequency of giant miniature end-plate potentials in 9 of 10 end-plates after 30 min and the number of miniature end-plate potentials which was maximum (562 3%, p<0.05) after 120 min. During the same period, the resting membrane potential decreased from – 81 1.4 mV to  – 41.3 3.6 mV 24 fibers; p<0.01; n=4) in the end-plate region and from – 77.4 1.4 to –44.6 3.9 mV (24 fibers; p<0.01; n=4) in regions distant from the end-plate. These results indicate that B. n. pauloensis venom acts primarily at presynaptic sites. They also suggest that enzymatic activity may be involved in this pharmacological action.

KEY WORDS: giant MEPPs, myotoxicity, neurotoxicity, presynaptic action.

CORRESPONDENCE TO:

L. RODRIGUES SIMIONI, Departamento de Farmacologia, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Cidade Universitária Zeferino Vaz, Caixa Postal 6111, 13083-970, Campinas, SP, Brasil. Phone: 55-19-3788-9534; Fax: 55-19-3289-2968. Email: simioni@obelix.unicamp.br.