[Hydrochloric acid secretion in stomach--new facts]

Spectrophotometric studies suggest that in aqueous solutions, gastric mucins (mucus) are subject to hydrolysis with secretion of I-V ions. Increasing mucins concentration in the solutions reverses hydrolysis and traps H+ ions. On this basis the hypothesis is proposed that the mucins secreted by the cells of the stomach mucous membrane are the source of the Hions.

In order to test this hypothesis an expenment was conducted based on measuring the pH values of solutions containing 0, 5, 10, 15, 20, and 30 mg of mucins in 100 cm3. The mucins were dissolved in distilled water, 0.9% NaCl, 1.0% KCl, and in aqueous HCl solution of pH 2.3.

The increase in mucins concentration in distilled water and in NaCl and KCl solutions causes a drop of pH: 7.0-->5.4; 7.5-->5.0 and 7.2-->5.4 respectively but in mucin-HGl solution pH value was constant.

The results obtained in this experiment permit the assumption that gastric acid (HGI) is being produced by the mucus layer during the blood electrolyte flow from the blood vessels lumen to the gastric lumen. Na+ and K+ ions included in the blood electrolyte are being exchanged for H+ of the mucus when CL- ions are running through it easily. The ion exchanger properties of mucus allow protecting gastric epithelium--during the back diffusion of W ions mucus exchanges them for Na+ and K+ ions that makes the gastric epithelium safe.