CALCITONIN-GENE-RELATED PEPTIDE (CGRP), A POTENT REGULATOR OF BILIARYFLOW

This study was designed to investigate the effect of porcine calcitoni n gene-related peptide (CGRP) on the motility of the porcine biliary t ract in vivo. We measured the pressure in the gallbladder and sphincte r of Oddi and, in separate experiments, the biliary flow into the duod enum during local intraarterial infusions of CGRP. To determine if the observed effect could be caused by release of cholecystokinin (CCK), we measured the CCK release. The basal pressure in the sphincter of Od di increased dose-dependently from 5.9 +/- 0.5 mmHg to 11.5 +/- 2.1 mm Hg and the motility index of phasic contractions (amplitude x frequenc y) from 47 +/- 8 to 347 +/- 64 mmHg s(-1), at an infusion rate of 32.6 pmol kg(-1) min(-1). No effect was observed on the gallbladder pressu re. CGRP at 6.5 pmol kg(-1) min(-1) significantly reduced the biliary flow into the duodenum to 47.7 +/- 6% of the basal level. Atropine, in jected intravenously, completely abolished the contractile effect of C GRP. CGRP had no effect on the release of CCK. We conclude that CGRP i ncreases biliary motility and hereby reduces bile flow, an effect whic h involves cholinergic but not cholecystokininergic mechanisms.