In vivo test of the ability of antiserum to myotoxin a from prairie rattlesnake (Crotalus viridis viridis) venom to neutralize local myonecrosis induced by myotoxin a and homologous crude venom.

Antiserum to myotoxin a was tested for its ability to prevent local myonecrosis induced by myotoxin a and C. v. viridis venom. Antiserum was injected i.v. either 5 min before or immediately, 15 min, 30 min, 1 hr or 3 hr after i.m. injection of toxin or venom. A light microscopic method was used to measure the effects of myotoxin a, i.e. vacuolation index, and whole venom, i.e. myonecrosis index. The results show that antimyotoxin a serum neutralizes the myotoxicity of a sublethal amount of myotoxin a if injected 56 min before or immediately after toxin, but not if injected 15 min after the toxin. Its neutralizing ability for crude C. v. viridis venom was considerably better, neutralizing a dose of 0.75 microgram/g even if injection of antiserum was delayed for 30 min after venom injection. Thus, antimyotoxin a serum might be useful in treating myonecrosis resulting from prairie rattlesnake (C. v. viridis) venom poisoning.