Abstract

To ascertain the role of the neuropeptide Y Y1 receptors in the vascular manifestations of the sympathetic baroreflex, 10-s bilateral carotid occlusions were performed in anesthetized cats; systemic blood pressure was monitored continually. This maneuver rose systolic blood pressure in 23±2 mmHg. Following 100 ?g/kg BIBP 3226 or BIBO 3304 i.v., the increase in blood pressure elicited by the occlusions was only 14±1 and 15 mmHg, respectively. Both BIBP 3226 and BIBO 3304 displaced significantly 5.5 fold rightward the pressor dose-response curve elicited by exogenous neuropeptide Y, without altering the norepinephrine curve. Prazosin (10 ?g/kg) reduced the pressor response elicited by the carotid occlusion to 12±4 mmHg. The simultaneous administration of BIBP 3226 plus prazosin rose the systemic blood pressure following the occlusion only 9±2 mmHg, supporting the involvement of neuropeptide Y in vascular sympathetic reflexes. Copyright (C) 1999 Elsevier Science B.V.