Topical prostaglandin E2 protects isolated gastric mucosa against acidified taurocholate-, but not ethanol- or aspirin-induced injury.

This study investigates whether topical prostaglandins protect isolated gastric mucosa against injury provoked by acidified "barrier-breaking" agents. Intracellular pH (pHi), apical cell membrane potential (Vcm) and intraepithelial resistances in isolated Necturus antral mucosa were measured using double-barreled liquid sensor microelectrodes. Topical PGE, treatment protected the antral mucosa against acidified taurocholate-induced injury, reducing significantly (P<0.05) intracellular acidification (pHi from 7.39+/-0.05 to 7.08+/-0.08 vs. from 7.30+/-0.02 to 6.62+/-0.15), and opposing significantly the changes in Vcm (hyperpolarization followed by depolarization), and completely abolishing the decrease in transmembrane resistance (Rt from 702+/-37 to 723+/-39 Ohms x cm2 vs. from 721+/-34 to 270+/-105 Ohms x cm2). Also the ratio of apical and basolateral membrane resistances (Ra/Rb) remained at a significantly higher level in PGE2-treated tissues. In contrast, PGE2 treatment had no protective influence on the changes of the respective parameters in acidified ethanol or acetylsalicylic acid injured mucosas. Topical prostaglandin E2 protects isolated gastric mucosa against acidified taurocholate, but not against ethanol- or acetylsalicylic acid-induced injury.