Effect of histamine and stress on the gastric mucosal Ca2+ content during the development of gastric ulcers.

The influence of histamine, its triazole derivative (3-beta-aminoethyl-1,2,4-triazole) and immobilization stress on the gastric mucosal Ca2+ content during the development of gastric ulcers in guinea pigs and rats was investigated. A considerable fall in the concentration of Ca2+ in gastric tissues of guinea pigs after administration of histamine 0.25 mg/kg, down to 80% (8.0 mumol/g), its derivative (1 mg/kg) to 72% (7.2 mucol/g) and stress to 76% (7.6 mumol/g) was recorded by atomic absorption-spectrophotometric techniques, while the calcium level in the controls stood at 9.9 mumole/g. Similar changes (90-65%) were seen in the blood plasma. In rats, the Ca2+-decreasing effects of stress ran closely parallel with increasing ulceration, and depended on the duration of stress. The immobilization of rats evoked a slight rise in the Na+ content of the gastric tissues. After 4 h immobilization, the tissue concentration of Na+ was increased to 116% of control levels. Cimetidine (100 mumol kg-1 more than 50% inhibited the development of gastric ulcers and prevented the change in Ca2+ concentration ions. Thus, the data suggest that Ca2+ ions take part not only in the regulation of secretion, but also in stress tissue dystrophy.