Antisecretory activity of 6-aminoindazole in rats.

Administration of 6-aminoindazole (6-AIN) and 5-aminoindazole (5-AIN) to rats depressed gastric acid secretion, both basal and carbachol-stimulated. 6-AIN proved to be more active than 5-AIN in decreasing the stimulated secretory process. The antisecretory activity of 6-AIN appears to be partially an antihistamine effect, since this compound antagonized the stimulatory action of betazole on isolated guinea pig auricle. The antisecretory activity of 6-AIN is probably associated with an antimuscarinic effect, since the molecule decreased carbachol-stimulated gastric acid secretion in rats and depressed neostigmine-stimulated motility of duodenum and colon in the anaesthetized cat. It also lessened the hypertonus of isolated guinea-pig trachea caused by pilocarpine. The antisecretory effects of 6-AIN also appear to be associated with myolytic activity, since it decreased the spontaneous motility of duodenum and colon in anaesthetized cats and the spontaneous myoactivity of isolated jejunum of the rabbit. It depressed the contractions of isolated guinea-pig ileum caused by histamine and decreased the spasmogenic effects of barium chloride on isolated guinea-pig gall bladder. These results suggest that 6-AIN probably depresses gastric acid secretion by interfering with both histamine and acetylcholine receptors and with other receptors involved in the secretory process.