Inhibition of pentagastrin-stimulated gastric acid secretion by graded intraduodenal administration of oleic acid in man.

The inhibitory effect of intraduodenally administered oleic acid in volumes of 5--40 ml on pentagastrin-stimulated gastric acid secretion was determined in healthy volunteers. In the control experiments, corresponding volumes of saline were given. Five and 10 ml oleic acid brought about a significant inhibition of gastric acid secretion of 29% and 32%, respectively. After 20 ml of oleic acid the inhibition was 46%, a significantly stronger inhibition than after 5 or 10 ml. Forty milliliters of oleic acid did not further increase the inhibition. Maximal inhibition appeared 30--60 min after the administration of oleic acid. In seven duodenal ulcer patients 20 ml oleic acid evoked an inhibition of gastric acid secretion of 20%, which was significantly less than the inhibition produced in healthy subjects after the same volume of oleic acid. The results suggest that the intraduodenal administration of relatively small volumes of oleic acid elicits a dose-dependent inhibition of pentagastrin-stimulated gastric acid secretion in man and that maximal inhibition is obtained by 20 ml of oleic acid. The results also indicate that duodenal ulcer patients may have a defective fat inhibitory mechanism.