Effect of bulbar acidification on gastric acid responses to urecholine in Pavlov pouch dogs.

Dogs were provided with mucosal septal pouches of the fundic stomach and of the duodenal bulb. Gastric secretion was stimulated by intravenous infusion of submaximal doses of porcine gastrin or the stable choline ester Urecholine. Acid perfusion of bulbar pouches profoundly inhibited acid responses to gastrin. Bulbar acidification produced little or no reduction in acid secretion induced by Urecholine. Small doses of Urecholine do not release gastrin in the dog but may induce acid secretion, mainly by direct cholinergic stimulation of the HCl glands. The fact that Urecholine-induced acid secretion was not inhibited in the present experiments is consistent with the hypothesis that the bulbar mechanism does not interfere with cholinergic stimulation acting on the parietal cells.