Defective bicarbonate secretion in response to duodenal acidification in patients with chronic gastric or duodenal ulceration.

Histamine infusion studies were performed in 54 healthy persons, in 58 patients with duodenal ulcers and in 29 patients with gastric ulcers. The acid load entering the duodenum was estimated by measuring the loss of an intragastric marker, phenol red. The volume of duodenal juice that had refluxed into the stomach and which was aspirated with the gastric juice was estimated by the sodium content of the aspirate. The bicarbonate concentration of the refluxed duodenal juice was calculated from the relationship between neutralisation and total electrolyte concentration, since the reaction of one bicarbonate ion removes two ions from the resultant mixture. The mean bicarbonate concentration of the refluxed duodenal juice in the control group was 116,4 (+/- 9) mEq/1, and the individual bicarbonate concentrations showed the expected dependence on the magnitude of the intraduodenal acid load. The mean bicarbonate concentration in patients with duodenal ulcers was 84,6 (+/- 9) mEq/1, which was significantly lower than in healthy persons. In patients with duodenal ulcers and in those with gastric ulcers, the reflux bicarbonate concentrations were independent of acid load. These results confirm previous reports of an impaired pancreatic bicarbonate secretion in response to duodenal acid load in patients with duodenal ulcers, and indicate a similar response in patients with gastric ulcers.