Antacid protection of gastric mucosa.

Antacids containing aluminum hydroxide are protective for the stomach in that they prevent grossly visible mucosal necrosis and hemorrhages produced by noxious agents such as aspirin or absolute ethanol. Histologically, this protective effect is confined mainly to the tissue located deep in the gastric mucosa, essentially comprising gastric glands, while the damage to the surface epithelium is not significantly lessened. Accordingly, integrity parameters of the superficial epithelial layer (potential difference, mucus secretion, cell desquamation) do not indicate a protective action of antacids against damage by necrotizing agents. By contrast, significantly diminished microbleeding rates do suggest that protection by antacids works at a level deeper within the mucosa. The protective action of antacids may be mediated, at least in part, by endogenous prostaglandins, which were found to be elevated in this context.