THE ACTION OF SYMPATHOMIMETIC AMINES ON THE ISOLATED HEART OF THE FROG

¹ Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania.

1. The isolated frog's heart shows epinephrine-like responses to 2-phenylethyl-amine derivatives with at least one hydroxyl group in either the 3- or 4-position on the ring. Compounds with secondary (methyl- or isopropylamino) or tertiary amine groups are also active.

2. When the side chain is lengthened to three carbon atoms, only 3,4-dihydroxy-phenyl compounds are active. l-Dihydroxyphenylalanine (DOPA) produces positive inotropic effects.

3. The aliphatic sympathomimetic amines produce positive inotropic changes which are reversible only with difficulty. Certain characteristics of the actions of these compounds indicate that the mechanism of action differs from that of epinephrine.

4. Phenyl- and cyclohexyl-alkylamines do not; possess positive inotropic activity.

5. Ergot alkaloids, Priscol, 2-(piperidinomethyl)-6-methoxy tetralone and dibenamine are unsatisfactory adrenolytic agents when applied to the frog's heart.