Demonstration of a pH gradient in the gastric gland of the acid-secreting guinea pig mucosa

The gastric mucosa is covered by a continuous layer of mucus. Although impo rtant for understanding the mechanism of this protective function, only sca rce information exists about the pH inside the gastric gland and its outlet . pH in the lumen of the gastric glands, in the outlet of gastric crypts, a nd in the adjacent cells was measured in the isolated acid-secreting mucosa of the guinea pig. Ultrafine double-barreled pH microelectrodes were advan ced at high acceleration rates through the gastric mucus and the tissue to ensure precise intracellular and gland lumen pH measurements. A pH gradient was found to exist along the gastric gland, where the pH is 3.0 at parieta l cells, i.e., in the deepest regions, and increases to 4.6 at the crypt ou tlet. Intracellular pH (pH(i)) of epithelial cells bordering a crypt outlet , and of neck cells bordering a gland, was acidic, averaging 6.0 and 6.5, r espectively. pH(i) of deep cells bordering a gland was nearly neutral, aver aging 7.1, and the secreting parietal cells were characterized by a slightl y alkaline pH(i) of 7.5. This gland pH gradient is in general agreement wit h a model that we recently proposed for proton transport in the gastric muc us, in which protons secreted by the parietal cells are buffered to and tra nsported with the simultaneously secreted mucus toward the gastric lumen, w here they are liberated from the degraded mucus.