Effects of α‐ and β‐calcitonin gene‐related peptides upon ion transport in rat descending colon

Abstract
Both α- and β-calcitonin gene-related peptide (CGRP) exhibit concentration-dependent dual actions upon rat colonic epithelia. At low concentrations (i.e. 0.03–10 nm) both CGRPs produce antisecretory effects that are abolished by pretreating tissues with tetrodotoxin (TTX). At higher concentrations (30–200 nm) secretory responses predominate and these effects are not abolished by TTX. It is suggested that the mediator of the antisecretory actions of CGRPs is somatostatin.