Myotoxicity of Crotoxin on C2C12 Myoblasts and its Inhibition by Crotalus Neutralizing Factor versus Enhanced Resistance in Myotubes: Exploring Toxicity and Membrane Potential.

Background: Crotalus Neutralizing Factor (CNF) is a γ-type Phospholipase A2 (PLA2) inhibitor present in the blood of Crotalus durissus terrificus snake. Particularly, CNF inhibits the toxic action of Crotoxin (CTX), which is a major neurotoxin found in C. d. terrificus venom. CTX induces also myotoxic action and demonstrates high selectivity for skeletal muscle fibers. Consequently, CTX can diffuse beyond the site of infection, which can potentially evoke rhabdomyolysis. The present study has evaluated the effects of CTX on myoblasts and myotubes of muscle cells C2C12 in vitro and the effect of CNF on CTX-induced damage.

Methods: Cytotoxicity assays were performed by measuring the mitochondrial enzyme dehydrogenase levels. Furthermore, creatine kinase and lactate dehydrogenase levels were used as indicators of muscle damage.

Results: Crotoxin has been found to have cytotoxic effects on C2C12 myoblast cells, while CNF has not shown toxic effects on these cells. Furthermore, the findings have shown CNF (50 μg/mL) to abolish CTX toxicity in myoblasts. The myotubes, differentiated cells, showed no change in mitochondrial respiration when exposed to CNF or CTX, showing greater resistance to the toxic actions of crotoxin.

Conclusion: The data have confirmed the potential of CNF as an anti-myotoxic agent to prevent CTX-damaged myoblasts and increase resistance to the toxic effects of crotoxin on differentiated cells.