A STUDY OF REFLEXES INVOLVING THE PYLORIC SPHINCTER AND ANTRUM AND THEIR RÔLE IN GASTRIC EVACUATION

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Abstract
HCl when placed in the duodenum of unanesthetized dogs with gastric and duodenal fistulas caused a temporary increase in the tonus and activity of the pyloric sphincter, followed by inhibition. HCl in the stomach had no significant effect on the sphincter. Acid and a variety of other substances including saline in sufficient volume when placed in the duodenum caused inhibition of digestive peristalsis in the pyloric portion of the stomach, even when used in concns. or amts. insufficient to increase the tonus of the sphincter. The normal accumulation of duodenal contents has a similar effect, because draining the duodenum during digestion constantly increased the force of the gastric peristalsis. Expts. performed after section of the appropriate nerves proved that the sphincteric contraction reflex due to acid is mediated by the myenteric mechanism and that the gastric and sphincteric inhibitory reflex is mediated mainly by the vagi. No evidence was found that any of the reflexes studied were mediated by the splanchnic nerves. The retarding effect of acid in the duodenum on gastric emptying is believed due to inhibition of gastric peristalsis and not to closure of the pylorus.

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