An acute experiment on retrograde intestinal peristalsis with emesis using decerebrated dogs

This acute experiment using decerebrated dogs was a new model for studies of central and peripheral mechanisms of intestinal motility with emesis, and was undertaken to clarify the relationship between intestinal contractions and the retrograde transport of intestinal contents with emesis. Contractility of the small intestine was recorded by five force transducers. Reflux of mannitol solution injected into the small intestine through the proximal duodenum was recorded by a magnetic flow meter. Retching was induced by vagal afferent stimulation, intramuscular apomorphine, or intragastric copper sulfate. Intestinal contractility was enhanced preceding retching caused by these emetic stimuli. Characteristic contractions in the oral direction were observed in the small intestine before and during retching. These contractions originated in the caudal or middle intestine and conducted to the duodenum intermittently, rather than continuously. Reflux of mannitol solution to the proximal duodenum was observed just after the initiation of retching, and was sometimes observed repeatedly during retching. These results suggest that intestinal contents are repeatedly transported to the proximal duodenum during retching by intermittent retrograde contractions. Acute experiments using decerebrated dogs seem to be useful and essential for studies of central and peripheral mechanisms of emesis.