Acid-Binding Capacity of Dialyzed Mucin Fractions from Human Gastric Juice.

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Abstract
Summary and Conclusions Electrometric titration of dialyzed visible gastric mucus recovered directly from the stomach of a man with a large gastric fistula and an occluded esophagus revealed an acid binding capacity, if calculated per gram of the dry substance, far smaller than that reported for undialyzed human or animal mucus; the acid binding capacity for mucoproteose and mucoprotein dissolved in gastric juice was even smaller than that for visible mucus. This suggests that dialyzable materials including mineral bases are chiefly responsible for the alkalinity of gastric mucus and the buffering of the HCl of the stomach. The total buffering capacity of mucous substances dissolved in gastric juice ranges from 10.3 ± 3.5 to 1.2 ± 0.4% of the free acid present depending upon the rate of acid and mucin secretion prevailing at the time. It is emphasized that this study has concerned dialyzed and refined mucous substances in the gastric juice. These experiments do not bear upon the ability of the visible gastric mucus which invests the lining of the mucous membrane of the stomach to protect the underlying columnar epithelial cells by physical means (9).