COMPARISON OF THE NEUROMUSCULAR ACTIVITY OF Crotalus durissus ruruima AND Crotalus durissus terrificus VENOMS IN MOUSE NERVE-MUSCLE PREPARATIONS

HERNANDEZ-OLIVEIRA, S.S.(1), BORJA-OLIVEIRA, C.R.(1), DAL BELLO, C.A.(1), TOYAMA, M.H.(2), MARANGONI, S.(2), RODRIGUES-SIMIONI, L.(1)

(1)Departamento de Farmacologia, FCM, Caixa Postal 6111, (2)Departamento de Bioquímica, IB, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brasil.

OBJECTIVES: We have compared the effects of Crotalus durissus ruruima and C. d. terrificus snake venoms on neurotransmission in mouse isolated phrenic nerve-diaphragm preparations. METHODS AND RESULTS: Indirectly stimulated (4 x threshold, 0.1 Hz, 0.2 ms) mouse phrenic nerve-diaphragm muscle preparations suspended in Tyrode solution were incubated with venoms for up to 120 min. At 1 mg/ml, C. d. ruruima and C. d. terrificus venoms increased the twitch-tension amplitude (34.7±5.0% and 47.7±12.6%, respectively, p<0.05 vs. pre-venom amplitude) after 10 min, to reach a maximum of 137.4±21.5% and  116.0±21.4%, respectively, after 40 min (p<0.05 vs. pre-venom amplitude).  This was followed by progressive, irreversible blockade (50% in 89.0±8.0 min and 93.7±11.5 min, respectively). At 10 mg/ml, C. d. ruruima and C. d. terrificus venoms produced an initial increase in twitch-tension amplitude (82.7±22.0% and 41.2±8.3%, respectively, p<0.05 vs. pre-venom amplitude) after 10 min, to reach a maximum of 166.5±28.6% and  106.3±21.5% (p<0.05 vs. pre-venom amplitude) after 30.0±5.7 min and 25.0±3.5 min, respectively. As with the lower concentration, this was followed by progressive, irreversible blockade (50% in 78.2±10.0 min and 62.5±5.3 min, respectively). At 5 mg/ml, the pharmacological effects of both venoms were not significantly different from those obtained with the other two concentrations. CONCLUSION: These results incate that the neuromuscular action of  C. d. ruruima venom in mouse phrenic nerve-diaphragm preparations is similar to that of C. d. terrificus venom.

Financial support: FAEP.

CORRESPONDENCE TO:

HERNANDEZ-OLIVEIRA, S.S., Departamento de Farmacologia, FCM, Caixa Postal 6111, Universidade Estadual de Campinas (UNICAMP), 13083-970, Campinas, SP, Brasil, Email: castrohernandez@yahoo.com