Calcitonin gene-related peptide: a potent modulator of coronary flow.

Calcitonin gene-related peptide (CGRP) has been identified in nerve fibers innervating cardiovascular elements and particularly in coronary arteries (CA). To investigate its potential role in modulating coronary blood flow, we injected rat-CGRP into the CA of pentobarbital anesthetized, open chest pigs. Significant dose-related increments in coronary flow were observed. The rise in coronary flow was characterized by unusually, slow onset, late peak and prolonged duration. Arterial pressure, heart rate (HR) and myocardial contractility were unchanged, except at the highest dose (3.0 nmol), which produced mild systemic hypotension and sinus tachycardia. Coronary levels of catecholamines and 6-keto-PGF1 alpha were unchanged by CGRP. The direct, sustained, and potent dilatory activity of CGRP, in coronary arteries of the pig together with anatomical CGRP localization in this site suggest a role for this neuropeptide in hemodynamic regulation.