The effects of myotoxin from midget faded rattlesnake (Crotalus viridis concolor) venom on neonatal rat myotubes in cell culture.

Neonatal rat myoblasts were isolated and grown in culture until they fused into multinucleated myotubes. A small percentage of the myotubes showed spontaneous contractions when maintained in Dulbecco's Modified Eagle's Medium with 10% fetal bovine serum. Incubation of mature myotubes (at least 3 days after fusion) with myotoxin II from Crotalus viridis concolor venom at a concentration as low as 18.5 nM caused a marked increase in the number of myotubes demonstrating contractile activity. The increase was apparent within 24 hr of myotoxin application. The response of the myotubes appeared to be specific since, of the proteins tested, only native myotoxins caused the increase in contractile activity. This tissue culture system offers a rapid screening assay that requires less time and fewer animals than the assays currently in use for determining myotoxic activity.