Comparative potency of carbachol, sham feeding, fundic distension and 16,16-dimethyl prostaglandin E2 as stimulants of human gastric bicarbonate secretion.

Abstract

Six healthy subjects in random order underwent gastric bicarbonate secretion investigations, including stimulation with increasing doses of the cholinergic agonist carbachol, sham feeding, fundic distension and gastric instillation of 16,16-dimethyl prostaglandin E2. Bicarbonate secretion was measured by a computer-based system which continuously recorded pH and PCO2 of the effluent in a high-volume gastric perfusion system. The peak 30 min gastric bicarbonate output in response to carbachol, 150 mg subcutaneously, was 114% (P less than 0.05). Vagal stimulation by sham feeding resulted in a corresponding increase of 112% (P less than 0.05), while fundic distension to a volume of 600 ml gave an increase of 114% (P less than 0.05). In comparison, the response to 80 micrograms 16,16-dimethyl prostaglandin E2 was much greater, the peak bicarbonate output being increased by 245% (P less than 0.05). Both sham feeding and fundic distension appear to be either submaximal stimuli of gastric bicarbonate secretion in man or may possess both stimulatory and inhibitory actions.