[Anti-arrhythmic action of cimetidine].
In anesthetized rats, cimeti-dine (CMT) 120 mg/kg iv significantly in-creased the doses of aconitine required to induce arrhythmia and death; the incidence of ventricular fibrilliation and mortality due to iv CaC12 144 mg/kg were decreased by CMT 60 and 120 mg/kg iv. The ar-thythmias induced by iv BaC12 240 Vg/min and by coronary occlusions in rats were also counteracted by iv CMT 75 and 120 mg/kg, respectively. In anesthetized rabbits, iv CMT 37.5 mg/kg delayed the onset of ventricular ec-topic beats and shortened the total du-ration of arrhythmia induced by iv ad-renaline 75 ug/kg. The doses of ouabain necessary to in-duce ventricular extrasystole and death were elevated by iv CMT 3.75 mg/kg.min-1 in anesthetized guinea pigs. The effective refractory period (ERP) of isolated rabbit left atria was prolonged significantly by CMT 0.225 and 0.45 mg/ml without affecting myocardial contrac-tility.