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In order to observe the effects of freeze-dried saliva of Agkistrodon caliginosus and Agkistrodon saxatilis, the Korean poisonous snakes, on the contractility and action potential of frog ventricular muscle cells, the isometric tension in a vertical chamber and the action potential in horizontal chamber were recorded and analyzed. The following results were obtained; 1. ED_50, to reduce the contractility was 4-8ug/ml in the case of A. saxatilis and 8-16ug/ml in the case of A. caliginosus which all were higher than that of A. brevicaudus and the inhibitory effect on the contractility was greater in the case of A. saxatilis than that of A. caliginosus. 2. In the case of A. saxatilis, APD_50(time to repolarize 50% of action potential amplitude) decreased from 820±80 ms to 710±60 ms, the overshoot and the V max(Maximum depolarization rate) decreased from 34±8 mV to 18±4 mV, from 98±8 V/s to 89±4 V/s respectively. 3. In the case of A. caliginosus, ADP_50 decreased from 880±70 ms to 720±40 ms, the overshoot and the V max decreased from 28±6 mV to 20±4 mV, from 89±8V/s to 77±12V/s, respectively. 4. Inhibition of contractility and overshoot potential were more prominent in A. saxatilis and APD_50 was more decreased in A. caliginosus. The above result showed that Korean snake venoms would decrease the ionic current underlying the rapid upstroke phase and slow inward currents by calcium ions simultaneously in a frog ventricular muscle cells.
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