The precipitability of pepsin by colloidal aluminum hydroxide

Summary

• 1. Colloidal aluminum hydroxide, when mixedin vitro with canine gastric juice in quantities sufficient to buffer its free hydrochloric acid completely, also removes quantitatively all the pepsin from the solution.

• 2. Complete removal of pepsin from gastric juice can be achieved with much smaller quantities of colloidal aluminum hydroxide if the free hydrochloric acid of the juice is buffered beforehand by sodium carbonate.

• 3. Colloidal aluminum hydroxide, when mixed with acid gastric juice in quantities smaller than those required for complete buffering of free hydrochloric acid in the juice, causes the formation of a characteristic protein-like precipitate, which carries down pepsin in quantities roughly proportional to the volumes of the precipitates.

• 4. Hydrochloric acid, in concentrations comparable with its concentrations in normal gastric juice, slowly dissolves the above precipitates and liberates pepsin. The recovery of pepsin under certain conditions is quantitative.

• 5. Observations on experimental animals prove that the above-described reactions can take place alsoin vivo; if colloidal aluminum hydroxide is introduced into the stomach, it exercises not only a pronounced “antacid” but also an “antipeptic” action, which may last for a considerable time after a single application.

Our thanks are due to Professor B. P. Babkin who supervised this work, and to John Wyeth & Brother, who furnished a supply of Amphojel.