LACK OF EFFECT OF 4-AMINOPYRIDINE ON ACUTE RESETTING OF THE TYPE-I CAROTID BARORECEPTOR

Acute resetting of the type I carotid baroreceptor was examined before and after exposure to 10(-4) M aminopyridine (4-AP), a blocker of the transient K+ A current (I-A), using a vascularly isolated carotid sin us preparation in thiopental anesthetized dogs. Type I baroreceptor fi ring patterns were analysed to determine threshold pressure (P-th) at different conditioning pressures. Additionally, the ability of 10(-4) M 4-AP to induce vasoconstriction in canine carotid sinus, internal ca rotid and common carotid artery vascular ring segments was tested as a possible contributing mechanism to resetting. Our findings demonstrat ed that 10(-4) M 4-AP did not alter acute baroreceptor resetting or in duce carotid artery vasoconstriction.