Effect of parietal cell vagotomy on acid secretory responsiveness to circulating gastrin in humans. Relationship to postprandial serum gastrin concentration.

To study the relationship between gastric acid secretion and serum gastrin concentration after vagotomy, gastric acid output and serum gastrin concentration were measured simultaneously during intravenous infusion of graded doses of human gastrin heptadecapeptide (G-17) in duodenal ulcer patients with parietal cell vagotomy and in unoperated patients with duodenal ulcer disease (controls). The curve relating serum gastrin concentration to gastric acid output was shifted downward and to the right after vagotomy; the peak acid output to G-17 was reduced by 50% (p less than 0.001). The serum gastrin concentration that produced half of peak acid output (EC50%) averaged 185.5 pg/ml after vagotomy and 74.1 pg/ml in controls (p less than 0.01). Mean basal and postprandial serum gastrin concentrations were twofold to threefold higher in vagotomy patients than in controls (p less than 0.005). However, when peak postprandial serum gastrin concentrations were used to predict acid secretion from curves relating serum gastrin to acid output, predicted acid secretion was only 12.6 mmol/h in vagotomy patients compared to 24.4 mmol/h in controls. Parietal cell vagotomy decreases "functional" parietal cell mass, as reflected by a 50% decrease in peak acid output, and also reduces the responsiveness of "functional" parietal cells to gastrin to such an extent that acid secretion is reduced after vagotomy despite basal and postprandial hypergastrinemia.