FURTHER EVIDENCES ON THE NATURE OF THE VASOMOTOR ACTIONS OF ETHYLNORSUPRARENIN

¹ From the Department of Pharmacology, Stanford University School of Medicine, San Francisco, California)

Chemically, it might be predicted from its structural formula that ethylnorsuprarenin would resemble epinephrine very closely in its pharmacological actions. The abrupt fall of blood pressure which it produces, like nitrites, rather than a sharp rise, might be taken as proof that it was not similar to epinephrine as to mechanism of action. However, a more thorough analysis of the various factors entering into the maintenance of the arterial pressure, would show that ethylnorsuprarenin was very similar to epinephrine in most respects. Actually, it was found to stimulate the same sympathetic vasomotor augmentors as epinephrine, as shown by repeated injections, and responses after ergotization, sympathetic degeneration, etc., and also the same vasodilator mechanisms as shown by atropine and physostigmine. Moreover, the actions on the various excised vessels and on various intact organs were very similar. The chief difference from epinephrine is that ethylnorsuprarenin has much more of a sympathetic vasodilator action, from a quantitative standpoint, and that this action, under normal circumstances, makes the compound predominantly depressor for the arterial blood pressure, at least according to the methods used thus far. It is believed that central and reflex venous reactions should be studied with this drug for sake of completeness and further possible explanation of the circulatory actions.

Such a combination of actions is unique, as far as well known compounds are concerned, although it is probable that some closely related amines of this series may act similarly. The combination of peripheral vascular relaxation and cardiac stimulation which the ethylnorsuprarenin produces, may be of some clinical value in cases of cardiac failure, either acute or chronic, where epinephrine is of dubious value because it so markedly increases the load of peripheral resistance. Administration of ethylnorsuprarenin to humans has yet to be made, so, at present, it is not possible to do more than point to the theoretically possible uses of this compound.