Neutralization of Gastric Acidity Following Pyloric Closure

Abstract

In previous experiments from this laboratory 1 it was shown that the neutralization of gastric acidity, studied by means of an acid test meal, was definitely accelerated by division of the pyloric sphincter. The present experiments show that closing the pylorus, partially or completely, produces the opposite effect, i. e., a delay or complete absence of neutralization of the acid test meal.

Two series of experiments were performed. In one a silk ligature soaked in 25% AgNO₃ was tied around the pylorus so that occlusion short of complete obstruction was achieved. The only animals studied were those which remained in good condition and did not vomit following the operation (6 dogs). For periods as early as a few days and as late as several months a marked and sometimes complete delay in the neutralization of the acid test meal (200 cc. of 5% HCl fractionally aspirated) was found over the control curve obtained before operation. Preoperative curves were obtained in all but one of these dogs. In 5 other dogs operated on as controls no changes were noted.

In 7 dogs a pyloric snare was installed at operation. This could be closed or opened at will by means of a silver tube brought out through a separate stab wound. Several days or weeks after recovery the acid solution was introduced and it was possible in 8 successful experiments by tightening or loosening the snare to produce definite changes in the curve of neutralization. During periods when the pylorus was occluded the acid was neutralized incompletely or not at all; on its release the acidity dropped as promptly and rapidly as in the normal animal.

These experiments add further evidence to the idea previously expressed that there is an actual pyloric control of gastric acidity presumably because the sphincter influences the degree of regurgitation of alkaline duodenal contents particularly pancreatic juice into the stomach.