Neurotoxic and myotoxic actions of crotoxin-like and Crotalus durissus cascavella whole venom in the chick biventer cervicis preparation.

Crotoxin from Crotalus durissus cascavella venom was purified by a combination of molecular exclusion chromatography (Superdex 75 column) and HPLC molecular exclusion (Protein Pack 300SW column). Neurotoxic and myotoxic effects from C. durissus cascavella whole venom and its main fraction, the crotoxin-like, were studied in the chick biventer cervicis (CBC) nerve-muscle preparation. Both venom and its crotoxin showed significant (p < 0.05) blockade of neuromuscular transmission at concentrations as low as 0.2-1, 5 and 25 microg/ml, but no significant effect has been shown with a concentration of 0.04 microg/ml (n = 5 each). The time required to produce 50% neuromuscular blockade with the venom and its crotoxin was 53.6+/-8.2 and 65.9+/-4.9 min (0.2 microg/ml), 29.7+/-1.9 and 34.3+/-1.9 min (1 microg/ml), 24.8+/-1.6 and 21.1+/-1.5 min (5 microg/ml), 20.9+/-3.7 and 20.1+/-1.4 min (25 microg/ml), respectively. The addition to the incubation bath of acetylcholine (55 and 110 microM) or KCl (20.1 mM), either before or after the venom or the crotoxin induced contracture in the presence of a total blockade, in all the concentrations used. Morphological analysis showed that the damage caused by C. durissus cascavella venom is stronger than that caused by crotoxin. The myonecrotic picture was more marked at higher venom and crotoxin doses (1, 5 or 25 microg/ml). Only at 25 microg/ml concentrations of the venom and crotoxin, marked muscle fiber changes were detected. We concluded that the crotoxin-like and the whole venom from C. durissus cascavella possess a preponderant and quite potent neurotoxic action in this preparation, and a myotoxic action which is observed only at higher doses.