Date of Award

1-1-1987

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physiology and Pharmacology

Abstract

Histamine is known to cause an H$\sb 1$-receptor mediated vasoconstriction and an H$\sb2$-receptor mediated vasodilation in the coronary vasculature of the rabbit heart. In this study we looked at the role that the adenyl cyclase-cyclic AMP system plays in mediation of the histamine response in the vascular smooth muscle. Change in perfusion pressure in the isolated rabbit heart was used as the index of change in vascular tone when histamine was added to the perfusate. The vascular response to histamine was then studied while cAMP levels were altered by adenyl cyclase potentiation and phosphodiesterase inhibition. After the physiological responses of the vasculature were recorded, the coronary arteries were isolated and assayed for cAMP content. The histamine mediated response was compared to cAMP levels and the correlation was found to be very highly significant. It is the conclusion of this study that the histamine H$\sb{1}$- and H$\sb2$-receptors interact to regulate the levels of cAMP, which is responsible for the mediation of the vasomotion seen in the rabbit coronary arteries in response to histamine.

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