THE ACTION OF ACETYL-STROPHANTHIDIN ON HEART MUSCLE

¹ Departments of Physiology and Pharmacology, University of Rochester School of Medicine and Dentistry, Rochester, N. Y.

The action of the synthetic aglycone, acetyl-strophanthidin, was studied in turtle heart preparations. Chemically this drug is similar to the genins of the commonly used digitalis glycosides and the molecule contains an unsaturated lactone ring. The action on the auricle was essentially vagal. Ventricular strips, either spontaneously beating or those rhythmically driven, early developed short periods of tachycardia. Contraction amplitude was reduced and muscle shortening occurred with relatively low concentrations. The threshold for electrical stimulation was lowered. Significant shortening of refractory period without impairment of contractility which is characteristic of digitalis action did not occur. Unless certain concentrations will make it possible to utilize the vagal action without the untoward ventricular muscle effects the drug does not appear safe for clinical practice.