Measurement of Gastric Bicarbonate Secretion

The gastric output of bicarbonate and prostaglandin E2 has been calculated using a perfusion technique before and after instillation of 100 mM hydrochloric acid into the stomach of seven healthy volunteers. A significant increase in bicarbonate output occurred from 258±38 [tmol/3() min during the basal period to 531±86 [tmol/3() min after return of the intragastric pH to neutral (p<()0()5). Prostaglandin E2 output also increased significantly from 410±136 pmol/30 min to 1002±194 pmol/30 min (p<()-05). The changes were caused mainly by an increase in gastric secretory volume with only non-significant increases in concentrations of bicarbonate and prostaglandin E,. The results suggest that mechanisms exist to adjust the rate of gastric bicarbonate secretion to the prevailing intraluminal pH and that this may occur through the release of prostaglandin E,.