STUDIES ON VERATRUM ALKALOIDS. XXVIII. THE ACTION OF THE ERYTHROPHLEUM ALKALOIDS ON THE SINGLE TWITCH AND ON THE "VERATRINE RESPONSE" OF THE SARTORIUS MUSCLE OF THE FROG

¹ Department of Pharmacology, Harvard Medical School, Boston, Massachusetts

The antiveratrinic activity of a series of erythrophleum alkaloids was examined in the isolated sartorius muscle of the frog. All alkaloids studied were active. As with the cardiac glycosides the potency of the alkaloids in antagonizing the effect of a given concentration of veratridine in skeletal muscle paralleled closely their positive intropic potency in the vertebrate heart. This parallelism extended also to a synthetic ester, dimethylaminoethanol pimelate, which differs from the native alkaloids only in the acid involved, and to the breakdown products.

The type of antiveratrinic activity of these alkaloids is similar to that of the cardiac glycosides. In both cases pretreatment does not prevent the appearance of a transient veratrine response. The development of the antiveratrinic effect depends upon activity of the muscle. The duration of the pretreatment does not influence the time course of the antiveratrinic action. This typical time course is therefore independent of a process of diffusion of the alkaloids to the site of action.