Amino Acids as Gastric Secretagogues

Abstract

In the course of our recent studies on the secretion of gastric pepsin, we examined the effects of small amounts of amino-acids administered by the technique of Tagawa 1 to Pavlov gastric pouch dogs. The volumes of juice obtained were too small to allow accurate calculations of the total pepsin contents to be made, and the volume of secretion obtained differed greatly from that reported by Tagawa. In the present study 13 amino-acids were tested: alanine, arginine monohydrochloride, aspartic acid, cystine, glutamic acid, glutamic acid hydrochloride, glycine, histidine monohydrochloride, leucine, isoleueine, phenylalanine, tyrosine and valine.

As has been emphasized by Ivy and Javois, 2 all of the amino-acids appeared to be rather weak secretagogues with but few exceptions. Contrary to the results of Tagawa, glutamic acid hydrochloride was found in our work to be the weakest instead of the strongest stimulant for gastric secretion. All of the free acids, with the exception of isoleueine, were found to be slightly more active than glutamic acid hydrochloride. The fact that glutamic acid was a more potent stimulus for secretion than its hydrochloride is directly opposite to the findings of Tagawa.

Isoleueine, arginine and histidine were found to produce from 2 to 3 times the volume of juice excited by the other amino-acids tested. The activity of histidine in this respect is particularly interesting in view of its close structural relationship to histamine. The potency of isoleueine argues against the view that the basicity of the other 2 active amino-acids is the chief factor upon which their secretagoguic activity depends.

These studies were conducted on 8 Pavlov gastric pouch dogs, at least 3 being used for each amino-aeid studied, and 2 of the animals serving throughout the entire series of observations.