Recovery from gastric mucus depletion in the intact guinea pig mucosa

Background: In developed countries one‐third of the population is infected with the gastric pathogen Helicobacter pylori. In the early stages of H. pylori‐induced gastritis, typical symptoms include gastric erosions and mucus depletions. Artificial mucus depletion was generated, demonstrating both consequent irritation and recovery processes in the mucosa. Methods: The mucus depletion was examined by removing a small cylinder of mucus from the surface of the explanted guinea pig corpus mucosa, leaving the epithelial surface intact. pH microelectrodes were inserted into the mucosa in vitro, measuring the epicellular mucus pH, the pH _i of the underlying epithelial cells and the pH inside the gastric glands during mucus regeneration. Using infrared microscopy, the same process of mucus layer renewal was followed in anaesthetized animals. Results: The depletion exposed the tissue surface to low luminal pH levels. At a luminal pH of 2.5, a decrease was observed in the crypt outlet pH and surface cell pH _i , while deeper cells were less affected. However, a subsequent neutralization in the deep gland lumen was found. During the repair process, a quarter of the mucus layer was regenerated within the first 5?min. This newly secreted mucus formed a structure similar to that before depletion. Within 45 min, pH _i and tissue‐near pH values had fully recovered. Conclusion: Following mucus depletion, there is a decrease in surface cell pH _i and crypt outlet pH values. The repair process is then characterized by extensive mucus secretion and local cessation of acid secretion.