Sodium channel blocking effect of scorpion venom on cultured mouse myocardiocytes

Myocardiocytes of mice were cultured. Action potentials were recorded with microelectrodes inside the cells. Scorpion venom from Buthus martensii Karsch 3.75 or 7.5 micrograms.ml-1 decreased the duration of action potential and all of the depolarization concerned parameters of myocardiocytes. The Vmax, TP, APA behaved apparently in a dosage-dependent way. Restoration happened after washing out. Tetrodotoxin 2.5 micrograms.ml-1 acted in a similar way. Nimodipine 3.0 micrograms.ml-1 led to a decrease in action potential duration. BaCl2 0.1 mmol.L-1 elongated the action potential duration, while decreased the parameters concerned with depolarization. These results indicate that the scorpion venom has Na+ channel blocking action.