Effects of graded amounts of intragastric calcium on acid secretion, gastrin release, and gastric emptying in normal and duodenal ulcer subjects.

We studied effects of graded concentrations of intragastric calcium on acid secretion, residual gastric volume, and serum gastrin and calcium levels. Intragastric titration was performed with solutions of isotonic mannitol or mannitol plus 2.5, 6, 16, 39, and 97 mM CaCl(2) in 10 normal and eight duodenal ulcer subjects. Acid secretion was significantly increased above control values by the two highest CaCl2 concentrations in normal subjects and by the three highest CaCl2 concentrations in ulcer subjects. Highest observed acid output to any concentration of CaCl2 was 55% of peak acid output to pentagastrin in normal subjects and 75% in ulcer subjects. Intragastric calcium also released gastrin; correlation between acid secretion and circulating gastrin was weak (r = 0.43, P less than 0.05). Serum calcium was slightly increased but did not correlate with acid secretion. Residual intragastric volume after both control and CaCl2 solutions was much less in ulcer than in normal subjects; calcium did not alter residual volumes.