Coora cardiotoxin (CTX) has been shown to induce contracture of the skeletal muscle possibly by releasing the membrance Ca++. 1) β-bungarotoxin (β-BuTX) fo bungarus multicinctus venom blocks neuromuscular (N-M) transmission presynatically at the motor nerne ending. 2,3) It has been postulated that the mechanism of β-BuTX on N-M transmission may involve a direct or an indirect inhibition of Ca++ uptake by mitochondria inside the nerve terminals. 4) Since Ca++-activated ATPase is required for the Ca++ uptake of the membrane, 5) it would be of int erest to see if these two toxins exerts effects on the membrane Ca++ by the inhibition of this enzyme activity.
