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Reserpine, serotonin, and histamine as well as stress were employed to produce dystrophic lesions in the gastric mucosa of rats. Analysis of stomach tissues revealed that agencies which reduced catecholamine concentration also decreased endogenous levels of pepsinogen. Concentrations of the zymogen were increased after parenteral administration of dopa, but were not changed by injections of α-methyl-dopa. The evidence supports the suggestion that catecholamines participate in the control of pepsin production and are involved in the secretory function of the stomach.

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Derivatives of 3-(β-aminoethyl)-1,2,4-triazole similar to histamine have been resynthesized and studied. Four well-known effects of histamine have been considered (the contractions of an isolated guinea pig terminal ileum, dog gastric acid secretion, contractile frequency of an isolated guinea pig right atrium, blood pressure lowering effect in cats). Newly synthesized compounds IEM-813 and IEM-759 exerted some selective effect on H₁-and H₂-receptors: IEM-813 showed greater affinity for gut-isolated H₁-receptors than for stomach and atrium H₂-receρtors, while IEM-759 mainly influenced H₂-receptors. Accordingly, the influence of 1,2,4-triazole analogues on H₁- and H₂-receptors is subject to structural demands.

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.