Re-evaluation of the role of cyclic AMP in histamine-induced gastric acid secretion.

The 600 x g particulate fraction of gastric mucosal scrapings from rats was incubated with 3H-metiamide which saturated available binding sites at a concentration of 1 muM. Scatchard plots showed a single component with a Kd value of 0.2 muM. Unlabelled cimetidine and histamine competed with 3H-metiamide binding. The 600 x g particulate fraction also contained all of the hormone and sodium fluoride sensitive adenylyl cyclase. Adenylyl cyclase activity was not altered by histamine, pentagastrin or carbachol but was increased during incubation with prostaglandin E1, secretin and epinephrine. These findings do not support the hypthesis that gastric secretion is mediated by intracellular accumulation of cyclic AMP.