Effect of graded amounts of acid instilled into the duodenum on pancreatic bicarbonate secretion and plasma secretin in duodenal ulcer patients and normal subjects.

Pancreatic bicarbonate secretion and plasma secretin were measured in response to graded amounts of hydrochloric acid (0.94, 1.88, 3.75, and 7.5 mEq per 5 min) instilled directly into the duodenum in duodenal ulcer patients and in normal subjects. These graded amounts of acid produced graded increases in pancreatic bicarbonate in both groups. Mean bicarbonate secretion was significantly greater in the duodenal ulcer patients than in the normal subjects basally and after the lowest dose of hydrochloric acid. Mean (+/- SE) peak 30-min bicarbonate output (in milliequivalents) after duodenal acidification was 3.0 +/- 1.0 in the duodenal ulcer patients and 2.1 +/- 0.6 in the normal subjects (P less than 0.5). A significant (P less than 0.05) increase in plasma secretin occurred after duodenal acidification, but the increase in the duodenal ulcer and normal subjects was not significantly different (P less than 0.2). These results indicate that pancreatic bicarbonate secretion and increase in plasma secretin in response to graded amounts of duodenal acid are at least as great in patients with duodenal ulcer as in normal subjects.