Supersensitivity of the Cat Heart to Catecholamine-Induced Arrhythmias Following Reserpine Pretreatment.

Abstract

The threshold doses of norepinephrine and epinephrine producing ventricular arrhythmias were determined in spinal (pithed) cats. Of 20 control cats, only 2 had norepinephrine thresholds of 3 [mu] g/kg or below while among 27 cats treated with reserpine 0.1 mg/kg/day for 7 to 28 days 13 had thresholds of 3 [mu]/kg or below (P = .02). In the case of epinephrine, 3 of 10 control cats had thresholds of 30 [mu]g/kg or below, whereas 19 of 26 cats treated with reserpine were within the range (P = .05). There was indication of increasing sensitivity to catecholamine-induced arrhythmias with increasing duration of reserpine pretreatment.