Electropharmacology of Potassium Canrenoate 1

Summary

The action of and interaction between ouabain and potassium canrenoate were determined using changes of transmembrane potential and contractile characteristics of isolated ventricle strips of guinea pigs. Concentrations of ouabain ≥ 3 × 10^-6 M were always arrhythmogenic and induced intrinsic rhythmicity in normally quiescent ventricular strips. Potassium canrenoate at 10^-4 M did not inhibit ouabain-induced arrhythmias or intrinsic rhythmicity. Although 10^-3 M potassium canrenoate inhibited ouabain-induced intrinsic rhythmicity, there was a severe and progressive depression in the contractile magnitude. It was concluded that effective concentrations of potassium canrenoate which will inhibit ouabain-induced ventricular arrhythmias compromise the contractile function of the heart to such an extent that this drug may have little or no value in overcoming digitalis intoxication.

The authors thank Roger L. Bergstrom, G. D. Searle and Co., for supplying the samples of potassium canrenoate (Soldactone) used in these experiments.