[The effect of pentagastrin on calcium ion concentration in gastric juice]

Calcium concentration in gastric juice is lower then other electrolytes. The mechanism of its transport remained unknown. The aim of the study was to evaluate influence of pentagastrin on calcium concentration in gastric juice in humans. Ten patients were examined (4 females and 6 males, mean age 46.8 range 33-67), four with duodenal ulcer, three with achalasia cardiae and three with Addison-Biermer anemia. Pentagastrin--PG (Cambridge Laboratories, Newcastle, United Kingdom) was injected subcutaneously after overnight fast in dose of 6 micrograms/kg of body weight. Nosogastric tube was located in body of the stomach near large curvature and connected to suction of--40 mmHg pressure. Gastric juice was collected during subsequent five 15 minutes periods (first fasted and four periods after stimulation with PG). Calcium concentration was measured in each sample by fluorescentic titration method with EGTA. Statistic analysis was performed with student "t" test. Mean fasted and stimulated calcium concentrations were 0.83; 0.44; 0.54; 0.37 and 0.95 mmol/l respectively. Ca2+ concentration range in fasted state from 0.21 to 1.75 mmol/l and from 0.07 to 0.27 mmol/l by maximal stimulation. Calcium concentration decreased immediately after stimulation (significance p = 0.0025). This strong effect persisted throughout the period of stimulation. Calcium output was 0.064; 0.029; 0.032; 0.018 and 0.17 mmol/15 min respectively. Two phases of decrease of the calcium output were observed: first, fast decrease immediately after pentagastrin injection and second, slower, between 30 and 45 minute after stimulation (p < 0.01 and 0.02 respectively). Calcium concentration in gastric juice decreases after stimulation with pentagastin (p = 0.0025). Calcium concentration was lower in Addison-Biermer anemia and higher in duodenal ulcer patients then in healthy control. We conclude that calcium ions are not actively secreted by gastric mucosa. Their presence in gastric juice is a result of leak from mucosal cells and remains opposite to their metabolic activity.