Serum gastrin and gastric acid responses to meals at various pH levels in man.

Serum gastrin and gastric acid responses to a test meal of 10% peptone were measured in six duodenal ulcer patients using intragastric titration at pH levels ranging from 5.5 to 1.0. In this way the pH profile for inhibition of serum gastrin release and gastric acid secretion was established. A peptone meal adjusted to pH 5.5 produced gastric acid similar to the maximal response to histamine. A graded decrease of pH of the peptone meal to 1.0 resulted in the progressive inhibition of the gastric acid secretion and the concomitant suppression of the serum gastrin level. Exogenous secretin given in graded doses ranging from 0.25 to 2.0 U/kg-hr caused a dose-related inhibition of gastric acid secretion and the suppression of serum gastrin level. The results of the study indicate that gastric acid secretion and the rise in serum gastrin levels in response to an experimental meal are less when the gastric contents become more acid. The mechanism may involve release of secretin from the small intestine by acid.