A dose response study of the effect on gastric acid secretion of synthetic human
gastrin-17 in doses of 50,200, and 500 ng/kg/h was performed in eight healthy volunteers and in eight patients with
duodenal ulcer. The study was repeated on a separate day during
intravenous infusion of
calcium gluconate (0.1 mmol Ca2+/kg/h). In healthy subjects the
acid response to the combined infusion of synthetic human
gastrin and
calcium did not significantly exceed the response to synthetic human
gastrin alone, in contrast with patients with
duodenal ulcer in whom the combined infusion did significantly improve
acid output compared with infusion of synthetic human
gastrin alone. The dose of synthetic human
gastrin required for half maximal
acid response (D50) was reduced in both groups but significantly more in patients with
duodenal ulcer. No difference in serum
gastrin concentrations or in serum
calcium concentrations were found. It is hypothesised that extracellular
calcium plays a role in
gastrin stimulated
acid secretion in man and that patients with
duodenal ulcer are more sensitive to this
calcium dependent mechanism than non-
duodenal ulcer subjects.