Abstract

4-(2-Isopropylamino-1-hydroxyethyl) methanesulfonanilide (MJ 1999) was found to be an effective beta adrenergic blocking agent with little or no intrinsic sympathomimetic activity. MJ 1999 antagonized the cardiac irregularities produced by the intravenous administration of a large dose of epinephrine. The drug also protected against the ventricular fibrillation produced by methylchloroform and epinephrine but did not suppress the ventricular arrhythmias due to ouabain or coronary artery ligation. These results provide additional support for the thesis that beta adrenergic blocking agents can antagonize sympathomimetic amine-induced arrhythmias by a mechanism which involves specific adrenergic blockade.