Antisecretory effect of imidazole and its derivatives in an isolated gastric mucosa preparation and an anesthetized young chicken preparation; comparison with a histamine H2-receptor antagonist.

We invesigated the influences of imidazole on the basal and the secretagogue-stimulated gastric acid secretion in isolated bullfrog gastric mucosa preparations and in anesthetized young chickens. Imidazoles (1 x 10(-4) g/ml) readily depressed the basal acid secretion in gastric mucosa in vitro. The inhibitory effect of imidazole was diminished considerably after washing out of the drug. The maximum acid secretion elicited by tetragastrin or bethanechol was completely antagonized by imidazole (1 x 10(-4) g/ml). The stimulatory action of histamine or dibutyryl cyclic AMP was also remarkably depressed in the presence of imidazole (3 x 10(-4) g/ml). after dibenamine pretreatment (5 x 10(-5) g/ml) for 60 min, the isolated gastric mucosa preparation became refractory to tetragastrin, bethanechol and histamine, but responded to dibutyryl cyclic AMP. Imidazole protected the histamine sensitivity against dibenamine blockade in the concentration of 5 x 10(-4) g/ml. In anesthetized young chickens, imidazole (200 mg/kg, s.c.) depressed tetragastrin- and histamine-stimulated gastric acid secretion. The effects of the imidazole derivatives and several antagonists (metiamide, atropine, diphenhydramine, acetazolamide and 2,4-dinitrophenol) on acid production were compared with that of imidazole. From these results, it is concluded that imidazole has a potent antisecretory effect on the basal and the secretagogue-stimulated acid secretion.