Variation in hydrochloric acid secretion during the digestive period

Abstract

These observations were conducted on dogs having Pawlow double stomachs. After test meals of hashed meat, alone or mixed with crackers and water, it was noted that the percentage of HCl in the gastric secretion varied somewhat during the digestive period. Estimations of the HCl were repeatedly made for each hour during the period, by the Volhard method of chlorine determination, after neutralization of the juice with NaOH and careful incineration. The total chlorides and the metallic chlorides were determined, and the difference between them reckoned as HCl. By the use of this method it became evident that the gastric secretion was higher in its content of HCl early in digestion than it was toward the end and that there was a general lowering of the acid percentage as digestion progressed, in the same way that there was a lessening in the amount of juice secreted. The amount of HCl in gastric juice in the first two hours of digestion was from 0.4 to 0.5 per cent., whereas in the last hour it sometimes fell to 0.2 per cent, or slightly lower. The acidity of the juice and to some extent the variation in secretion varies with different dogs and with different diets, but with any one animal the response elicited by a certain test meal is remarkably constant, and the curves of acid secretion, like the curves for the amounts of juice secreted, are uniform.