Effect of Hydrazine on Aconitine-Induced Atrial Tachycardia in the Rabbit

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Except positive inotropic action, hydrazine has been detected to have negative chronotropic and dromotropic actions in the rabbit's atrial and bullfrog's ventricular muscles. Aconitine-induced atrial tachycardia in rabbits and spontaneously beating ventricular tachycardia in bullfrogs were promptly converted to bradycardia by hydrazine. The mechanisms of these actions of hydrazine were concluded to result from (1) a prolonged refractory period, (2) a suppression in automaticity, (3) the increase of threshold, and (4) the delayed conduction velocity.