The vagus, the duodenal brake, and gastric emptying.

It has been suggested that an intact vagal supply is essential for the normal function of the recptors in the duodenum and proximal small bowel, which influence the rate of gastric emptying. This paper reports the effect of vagal denervation on gastric emptying and also examines the site and mode of action of receptors in the proximal small bowel. It has been demonstrated in the dog that most, if not all, the receptors controlling gastric emptying lie in the proximal 50 cm of the small bowel. Following truncal vagotomy the emptying time of each instillation increased significantly and the differential rate of emptying of different instillations remained unchanged. The proximal 50 cm of small bowel was capable to differentiating between different instillates even after selective extragastric vagotomy, in which the duodenum was vagally denervated and, therefore, duodenal braking receptors function independently of vagal innervation.