Calcitonin gene-related peptide is a potent relaxant of intestinal muscle

The motor effects of calcitonin gene-related peptide (CGRP) on the guinea-pig ileum (GPI) longitudinal muscle were investigated. CGRP (0.1-100 nM) concentration dependently relaxed ilea precontracted with histamine and inhibited electrically induced cholinergic contractions. At higher concentrations (3-100 nM) CGRP also caused a slight contraction of non-stimulated ilea. Further pharmacological analysis of the CGRP-induced relaxation which seems to be the primary CGRP effect in the GPI, indicated that the effect was due to a direct action on the longitudinal muscle.