Effect of rising intragastric pH induced by several antacids on serum gastrin concentrations in duodenal ulcer patients and in a control group.

The interrelationship of the effects of antacids and of rising intragastric pH on serum gastrin levels was examined by comparing the effect of three antacids (Mg(OH)2Al(OH)3, and CaCO3), and their nonbuffering chloride compounds (MgCl2, AlCl3, and CaCl2), on serum gastrin and intragastric pH in duodenal ulcer patients. In the case of calcium, the effect of CaCl2 with a pH of 10, and in another group, CaCl2 with a pH of 2, was studied. In the case of magnesium, a control group was also investigated. In another group, the effect of a nonionized suspension (BaSO4) was studied in order to assess the contribution of intragastric volume. Serum gastrin was determined radioimmunologically, and pH measurements were performed in vitro using a glass electrode. Serum gastrin concentrations rose significantly whenever intragastric pH was raised. Serum gastrin also rose after MgCl2, AlCl3, and CaCl2 with a pH of 2, when intragastric pH was not significantly altered. This rise, however, was significantly smaller than after administration of the antacids, except in the MgCl2-Mg(OH)2 and in the CaCl2 pH 10-CaCO3 groups. No significant rise of serum gastrin levels was observed after BaSO4. In nonulcer subjects, gastrin response was smaller than in the duodenal ulcer patients. The results suggest that administration of nonbuffering Mg-, Al-, and Ca-chlorides leads to elevated serum gastrin levels in duodenal ulcer patients; rising intragastric pH, however, exerts an additional serum gastrin response.