Calcitonin gene-related peptide inhibits acid secretion without modifying blood flow

Calcitonin gene-related peptide (CGRP) is a 37-residue peptide present in the central and peripheral nervous system. Based on previous reports of its localization in fibers associated with vascular smooth muscles of vessels and its potent inhibitory effect on acid secretion, we studied the influence of intravenous infusion of rat CGRP on gastric mucosal blood flow. The hydrogen gas-clearance technique was used to measure mucosal blood flow in urethan-anesthetized rats. CGRP infused intravenously in doses of 1 or 10 micrograms X kg-1 X h-1 did not significantly modify basal gastric corpus mucosal blood flow or mean-arterial blood pressure. Gastric acid secretion stimulated by pentagastrin infusion (20 micrograms X kg-1 X h-1) was suppressed by CGRP administration (10 micrograms X kg-1 X h-1), whereas neither gastric corpus mucosal blood flow nor mean arterial blood pressure were significantly changed. These results indicate that CGRP must exert its inhibitory action on gastric acid secretion by a mechanism other than decreasing gastric mucosal blood flow.