Continuous computerized determination of gastric bicarbonate secretion in man.

A method for continuous determination of gastric bicarbonate secretion in man has been developed. A computer-based system calculated the total bicarbonate secretion every 30 sec throughout the experiment on the basis of the continuously recorded pH and Pco2 measurements. A high gastric perfusion rate facilitated the identification of duodenogastric reflux, which was observed as rather short-lived spikes on the curves. The contribution of alkaline saliva to the measured gastric bicarbonate secretion was minimized by continuous salivary suction and was corrected for after determining amylase in the gastric aspirate. Validation of the measuring system, by introducing bicarbonate in the range of 50-400 mumol into the stomach, demonstrated a correlation value of 0.91 (p less than 0.001) between added and recovered bicarbonate. Basal gastric bicarbonate output in seven healthy subjects was 379 +/- 105 mumol/h (mean +/- SEM). Intragastric instillation of 16,16-dimethyl prostaglandin E2 in five subjects resulted in a fourfold increase in gastric bicarbonate output.