A basic relationship between gastric and duodenal motilities in chickens.

Chickens were chronically fitted with a duodenal cannula and pairs of electrodes implanted in the wall of the muscular stomach, duodenum and ileum. Smooth muscle electrical activity was recorded in both fed and fasted conditions under a 12--12 h dark-light schedule. Two major patterns of activity were identified. The first consisted of spike bursts that propagated rapidly either aborally from the stomach or orally from the ileum. Aborad-propagated spike bursts were most frequent during the daytime; this circadian variation was abolished by vagotomy, which also increased the frequency of orad-propagated spike bursts. The second pattern was characterized by periods of repetitive spike bursts lasting 3--10 min and spreading aborally at a slower rate. In the fasted chicken, the daily frequency was increased and the period of repetitive spike bursts resembled the prolonged bursts of spike potentials recorded in the feline small intestine. The results suggest that the propulsion of digesta might depend on the ratio of spike bursts moving aborally from the stomach to those moving orally from the ileum. Both factors were influenced by the level of stomach activity.