INFLUENCE OF SEVERAL AUTONOMIC BLOCKING AGENTS ON SEGMENTAL VASCULAR REACTIVITY

¹ Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota

The influence of intravenously administered tetraethylammonium (TEA) on the vasoconstrictor response to norepinephrine and angiotensin in the acutely sympathetically denervated hindlimb was examined. It was found that there was no significant increase in the magnitude of the response in the small vessel or venous segments or in the total bed to either pressor agent. The t of the response to norepinephrine, however, was significantly increased. Acute denervation of the limb alone did not cause a significant increase in the magnitude or in the duration of the response to norepinephrine.

Administration of cocaine after TEA potentiated the arterial and venous constrictor response to norepinephrine, but small vessel vasoconstriction was essentially unchanged. The duration of the response to norepinephrine was greatly prolonged by cocaine. TEA and cocaine probably exerted additive potentiating effects since arterial constriction produced by angiotensin was also increased in magnitude. The administration (i.v.) of bretylium resulted in a similar pattern of potentiation of the response to norepinephrine in the innervated hindlimb as was obtained with cocaine in the denervated extremity.