Pretreatment with mild irritant enhances prostaglandin E2 release from isolated canine gastric mucosal mast cells.

Endogenous prostaglandin E2 has been indicated to have an important role in preventing gastric mucosal damage from noxious agents (i.e., in adaptive cytoprotection). However, the response of endogenous prostaglandin E2 to a mild irritant is controversial. In this study, we attempted to determine whether pretreatment with a low concentration of ethanol could induce endogenous prostaglandin E2 production by isolated canine fundic mucosal cells and to identify cells that are responsible for an increase of prostaglandin E2 production. Canine fundic mucosa was digested by collagenase, dispase, and EDTA. The cells were separated into five fractions with an elutriator rotor. Pretreatment with 5% ethanol induced a significant increase of prostagladin E2 release only from the secondary small-sized cell fraction, which was rich in mast cells and endocrine cells, and not from the other four fractions. Further cell separation by density gradient centrifugation revealed that the mast cell-enriched fraction (54%) was responsible for the increase of prostaglandin E2 release induced by the pretreatment with 5% ethanol. The results suggest that mast cells of the gastric mucosa play an important role in the production of endogenous prostaglandin E2 in adaptive cytoprotection.