Observations on Ionic Movement Through the Gastric Mucosa

From studies on the isolated gastric mucosae of amphibia and of the stomach in the intact mammal, there has emerged a simple description of the secretion of acid. There are two primary active transport systems, one for chloride and the other for the hydrogen ion. Chloride is transported somewhat more rapidly than the hydrogen ion. The difference between these two rates is substantially independent of the rate of acid production and constitutes a net current of negative ions moving from serosa to mucosa. Consequently a relatively constant electrical current is generated which accounts for the characteristic transepithelial potential difference. Water is assumed to move passively in response to he transport of these solutes, but clearly much more needs to be known about the kinetics of solvent flow (1). The variation in the com-position of gastric juice as a function of flow, which led to the unresolved controversy between Teorell and Hollander, indicates that there is a more or less constant leak or secretion of sodium. Perhaps potassium may approach a diffusion equilibrium between interstitial fluid and gastric juice, though in species other than man the electrochemical potential of potassium in the secretion is less than that in plasma