Bioassay of inhibitory activity of gastrone on basal HCl secretion in rats with chronic gastric fistula.

The authors evaluated the applicability of the rat with gastric fistula to the bioassay of gastrone, endogenous inhibitor of gastric acid secretion and the role of anticholinergic mechanism in this inhibition. 104 individual bioassays were performed on 25 rats with chronic gastric fistula out of which 34 tests were performed with gastrone, 49 controls with saline and 21 with atropine. In rats serving as their own controls, a statistically significant reduction of the volume of basal gastric secretion and of the basal HCl output by 56 and 59%, respectively, occurred after intravenous administration of 40 mug gastrone B. This was demonstrated in the first 4 h after gastrone and was statistically highly significant (p less than 0.001). There was no significant difference, however, in the concentration of HCl in the gastric juice after gastrone and after saline. The inhibitory effect of gastrone on HCl output at the intravenous dose of 40 mug was greater than that of 0.1 mg/kg atropine intravenously, while that of 50 mug gastrone was about equal to that of 0.4 mg/kg atropine. The gastrone inhibitory activity on gastric acid secretion in rats appears to be unrelated to anticholinergic mechanism. The advantages of the bioassay of gastrone activity using rats with chronic gastric fistula over the rats with pyloric ligation are discussed.