Effects of glycine and other instillates on concentration of gastric acid

Abstract

Instillation of isosmotic glycine solution on the mucosal surface of the histamine-stimulated canine stomach increases the concentration of HCl beyond its value in gastric juice. This was found to be primarily due to a reduction in the rate of water flow toward the lumen. Other instillates, including isosmotic sucrose, mannitol, and NaCl also produced an increase in the measured acidity. The effect is therefore not exclusively a result of the buffering of H ions by glycine. Instillation of urea did not significantly change the secreted acidity, and HCl instillation was accompanied by a decrease in acidity. The results can be most easily explained by assuming that the water component of gastric acid flows in response to an osmotic gradient due to secreted HCl. Instillation of the more impermeable solutes (sucrose, mannitol, NaCl) presumably reduces this gradient by dilution, while glycine acts in addition to reduce the gradient by buffering H ions.