Effect of vagal denervation on canine gallbladder motility

There is an increased incidence of gallstones after truncal vagotomy but the mechanism is unknown. Our aim was to study the early effects of vagotomy on fasting and postprandial gallbladder motility. A chronic model was constructed in 10 dogs to correlate gallbladder motility and emptying with interdigestive and postprandial duodenal motility both before and after selective hepatobiliary vagotomy (five dogs) and truncal vagotomy (5 dogs). During each study recordings were made for one complete interdigestive motor complex (IDMC) and for 90 min after a standard meal of (a) gallbladder and duodenal motility, (b) gallbladder emptying (by a dual radioisotope marker technique) and (c) duodenal output of bilirubin. In control studies the gallbladder contracted at the start of phase II of the interdigestive motor complex and ejected 20-25 per cent of its contents into the duodenum; after meals the gallbladder contracted within 5 min and emptied almost 80 per cent of its contents within 90 min. After both selective hepatobiliary vagotomy and also truncal vagotomy there was no significant difference in the pattern of contraction or emptying of the gallbladder either during fasting or postprandially. We conclude that gallbladder motility and emptying are entirely normal in the early period after vagal denervation.