Vagal influence on duodenal motor activity.

The extrinsic and intrinsic vagal influences on duodenal motor activity in the anesthetized dog were investigated. The following conclusions were derived: (1) Electrical vagal stimulation elicits gastroduodenal contractions. (2) Poststimulatory contractions, or off responses, occur on the antrum and duodenum after termination of the stimulus. (3) Denervation of the extrinsic vagal nerves to the duodenum does not eliminate the above responses. (4) Denervation of the extrinsic nerves to the duodenum and transection of the gastroduodenal junction eliminates stimulated duodenal motility and the occurrence of off responses on the duodenum. Antral responses remain unaffected. (5) The motor innervation to the duodenum is composed of extrinsic vagal fibers and intrinsic vagal nerves which appear to first enter the antrum and then cross the gastroduodenal junction to innervate the duodenum.