Impaired gastric acid secretion in mast cell-deficient mice

Gastric acid secretion in normal (+/+) C57B1/6J mice and congeneic, mast cell-deficient (mi/mi) C57B1/6J mice was examined. The mast cell-deficient animals had approximately 50% of the normal quantity of gastric histamine and a blunted basal acid level and secretory response. These observations were noted despite the presence of parietal cells, which were normal in number and morphology. The H2-antagonist ranitidine inhibited basal acid secretion in both groups of animals. Exogenous histamine induced a significant secretory response in normal and mast cell-deficient groups, but only the secretory response in normal animals could be blocked by the H2-antagonist. Treatment of mast cell-deficient animals with histamine for seven consecutive days before stimulation did not restore the histamine response to the normal (+/+) levels. The normal animals demonstrated an acid secretory response to pentagastrin. Mast cell-deficient mice also responded to pentagastrin, but the response was less than that observed in the normal animals, and a significant difference was not evident in all experiments. Furthermore, simultaneous injection of mast cell-deficient animals with histamine and pentagastrin did not restore pentagastrin responsiveness to normal levels, although the histamine concentration used was sufficient to raise acid secretion to basal levels of normal mice. These results support the conclusion that non-mast cell histamine only partially contributes to basal gastric acid secretion and is insufficient to facilitate full parietal cell responsiveness. Furthermore, pentagastrin requires the presence of mast cells to elicit a maximal secretory response but can use non-mast cell histamine to activate the parietal cells for acid secretion.