%0 Journal Article %A You-Tang Shen %A Tamara J. Pittman %A Pamela S. Buie %A David L. Bolduc %A Stefanie A. Kane %A Kenneth S. Koblan %A Robert J. Gould %A Joseph J. Lynch, Jr. %T Functional Role of α-Calcitonin Gene-Related Peptide in the Regulation of the Cardiovascular System %D 2001 %J Journal of Pharmacology and Experimental Therapeutics %P 551-558 %V 298 %N 2 %X It remains unknown whether the extent of vasoactive response to exogenous calcitonin gene-related peptide (CGRP) varies among different regional vascular beds. It is also unclear whether endogenous CGRP plays a functional role in regulating basal vascular activity. To address these two issues, experiments were conducted in 27 anesthetized rats instrumented with a carotid flow probe and catheters in a jugular vein, left ventricle (LV), and femoral artery, and in 6 conscious dogs, chronically instrumented with LV pressure gauge, aortic and atrial catheters, and ascending aortic, coronary, carotid, and renal flow probes. In both species, administration of human α-CGRP (0.1–0.5 μg/kg, i.v.) induced a dose-dependent peripheral vasodilation that was completely abolished by pretreatment with α-CGRP[8-37] (30 μg/kg/min, i.v.), a competitive antagonist of CGRP receptors. Regional blood flow measured by the radioactive microsphere technique in rats showed that the α-CGRP (0.3 μg/kg, i.v.)-induced increase in blood flow was greater (p < 0.05) in the heart (+53 ± 16%) than in the brain (+14 ± 6%). In the presence of β-adrenergic receptor blockade with propranolol, however, the increases in blood flow in these two vascular beds were identical. In conscious dogs, α-CGRP (0.3 μg/kg, i.v.) produced similar increases in coronary (+24 ± 6%), carotid (+26 ± 3%), and renal (+26 ± 6%) blood flow, which were different from the patterns induced by other vasodilators; at an equivalent level of reduction in mean arterial pressure and total peripheral resistance, α-CGRP increased coronary and carotid blood flow significantly less (p < 0.05) than adenosine or nitroprusside. Unlike α-CGRP, adenosine and nitroprusside, as expected, induced pronounced differential blood flow changes in these vascular beds. Neither systemic hemodynamics nor regional blood flow distribution was altered by the administration of a pharmacological blocking dose of α-CGRP[8-37] in the two species. Thus, we conclude that endogenous α-CGRP does not play an important role in cardiovascular regulation under normal, resting conditions, although exogenous α-CGRP induces a marked, comparable vasorelaxation in different regional vascular beds. The American Society for Pharmacology and Experimental Therapeutics %U https://jpet.aspetjournals.org/content/jpet/298/2/551.full.pdf