Effect of pH changes on the cardiac sphincter.

In 16 normal subjects the pressure characteristics of the cardiac sphincter have been examined. The effect of perfusing the gastric aspect of the sphincter mucosa has been studied by comparing the effects of saline with those of solutions where pH ranged from 1.0 to 8.0. Acid perfusion produced an increase in sphincteric pressure, particularly at pH 3.0. This suggests that a physiological mechanism exists which can increase the barrier pressure to gastrooesophageal reflux during periods of active secretion of the stomach, as occurs in digestion.