A STUDY OF THE MECHANISMS OF THE MODIFYING ACTIONS OF COCAINE, EPHEDRINE AND IMIPRAMINE ON THE CARDIOVASCULAR RESPONSE TO NOREPINEPHRINE AND EPINEPHRINE

Abstract

Cocaine was shown to enhance the action of norepinephnine and epinephnine on systemic blood pressure by a combination of three mechanisms: (1) a peripheral enhancement shown in the perfused limb, (2) an inhibition of the vasodilator reflex induced by the two catecholamines, (3) an increase in the blood levels of active circulating amines following their injection.

These three mechanisms could also be demonstrated for the enhancement of norepinephrine and epinephnine by ephednine but it appeared that the latter two were of greater importance.

Imipnamine enhanced the action of norepinephrine but reduced the action of epinephrine on systemic blood pressure. It reduced the action of epinephrine in the perfused leg and had an inconsistent influence on the action of norepinephrine. Imipramine blocked the vasodilator reflex induced by both and increased the levels of circulating norepinephrine.