Calcitonin gene-related peptide (CGRP), a potent regulator of biliary flow

Abstract This study was designed to investigate theeffect of porcine calcitonin gene-related peptide(CGRP) on the motility of the porcine biliary tract invivo. We measured the pressure in the gallbladder andsphincter of Oddi and, in separate experiments, thebiliary flow into the duodenum during local intra-arterial infusions of CGRP. To determine if theobserved effect could be caused by release of cholecys-tokinin (CCK), we measured the CCK release. Thebasal pressure in the sphincter of Oddi increaseddose-dependently from 5.9 + 0.5 mmHg to11.5 + 2.1 mmHg and the motility index of phasiccontractions (amplitude 6 frequency) from 47 + 8to347 + 64 mmHg s 71 , at an infusion rate of32.6 pmol kg 71 min 71 . No effect was observed on thegallbladder pressure. CGRP at 6.5 pmol kg 71 minsignificantly reduced the biliary flow into the duode-numto47.7 + 6%ofthebasallevel.Atropine,injectedintravenously, completely abolished the contractileeffect of CGRP. CGRP had no effect on the release ofCCK.We conclude that CGRP increases biliary motilityand hereby reduces bile flow, an effect which involvescholinergic but not cholecystokininergic mechanisms.Keywords biliary motility, gastrointestinal motility,neuropeptides, sphincter of Oddi,.