title: Calcitonin gene-related peptide (CGRP) is a potent non-endothelium-dependent inhibitor of coronary vasomotor tone.
abstract: 1 Ring segments of bovine left circumflex coronary artery were pre-contracted with 5-hydroxytryptamine or phenylephrine and then exposed to increasing concentrations of calcitonin gene-related peptide (CGRP) and other drugs. 2 CGRP administration resulted in dose-dependent inhibition of induced tone. Maximal relaxation to CGRP was 89 +/- 5% and the concentration required to achieve 50% maximal relaxation (EC50) was 2.11 +/- 1.35 X 10(-9)M. 3 CGRP-induced relaxation was not affected by removal of endothelial cells nor was it significantly altered by incubation of coronary vessels with atropine, propranolol, phentolamine (all 10(-6)M) or indomethacin (10(-5)M). 4 From these data we conclude that CGRP is a potent inhibitor of coronary artery vasomotor tone which appears to act directly on vascular smooth muscle rather than through the release of a secondary mediator. These data support the possibility that CGRP may play a role in non-adrenergic, non-cholinergic regulation of coronary artery tone.
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide; D002417:Cattle; D003331:Coronary Vessels / Q000187:drug effects*; D004727:Endothelium / Q000502:physiology; D066298:In Vitro Techniques; D009126:Muscle Relaxation / Q000187:drug effects; D009129:Muscle Tonus / Q000187:drug effects; D009479:Neuropeptides / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D009479:Neuropeptides; D014665:Vasodilator Agents; D015740:Calcitonin Gene-Related Peptide