AN ANALYSIS OF THE REVERSAL OF THE TRYPTAMINE DEPRESSOR EFFECT IN THE CHICKEN BY DIPHENHYDRAMINE AND TRANYLCYPROMINE

¹ Biomedical Research Department, Pitman-Moore Company, Indianapolis, Indiana, A Division of The Dow Chemical Company

Diphenhydramine antagonized the increase in pulmonary resistance caused by intravenous tryptamine in chickens, but had relatively less antagonism to the peripheral vasoconstrictor effects. The systemic depressor effect of tryptamine was either blocked or reversed by diphenhydramine.

Methysergide was also an effective antagonist to the pulmonary effects of tryptamine and blocked the effects of tryptamine on systemic blood pressure.

The monoamine oxidase inhibitor, tranyl-cypromine, induced a supersensitivity to tryptamine in the peripheral and pulmonary vasculature but the effect on the latter was of shorter duration. The systemic depressor action of tryptamine was reversed. Harmine induced similar changes.

The potentiation of the tryptamine effects in the chicken by monoamine oxidase inhibitors was shown not to be directly related to a possible prolongation of plasma half-life.