Electrophysiologic Effects of Potassium Canrenoate on Ouabain-Induced Ventricular Dysrhythmias in Rabbits

Abstract

The effects of i.v. injections of 0.05 mM (20 mg)/kg potassium canrenoate and equimolar (3.75 mg/kg) potassium chloride on ventricular tachycardia (VT) and ventricular fibrillation (VF) induced by i.v. infusion of ouabain (2 µg·kg^-1 • min^-1) were studied in 46 rabbits anesthetized with sodium pentobarbital. Ventricular tachycardia occurred after a mean dose of 110µg of ouabain in 32 rabbits divided into three groups: eight control rabbits received no treatment after the onset of VT, 18 received potassium canrenoate and six received potassium chloride. Within 1 min following the first injection of potassium canrenoate, VT was converted into sinus rhythm in each of the 18 rabbits; however, in 11 rabbits additional injections of the drug were necessary to achieve a sustained conversion. Potassium chloride injections failed to convert VT in the six rabbits so treated. Ventricular fibrillation was induced in 14 rabbits after a mean dose of 160 µg of ouabain. Even VF could be converted into sinus rhythm by potassium canrenoate in four of eight rabbits. Equimolar potassium chloride treatment had no effect on VF in the remaining six rabbits. These data further demonstrated the effectiveness of canrenoate in experimental dysrhythmias induced by ouabain.