A fluorescent in vivo microscopic method to assess surface mucosal integrity in the rat stomach. Effects of ethanol and prostaglandin.

A new sensitive in vivo fluorescent method to assess gastric mucosal integrity in the anesthetized rat is described. Topically applied fluorescein diacetate enters gastric mucosal cells. The diacetate is cleaved by intracellular esterases leaving fluorescein trapped within the cells. The pattern of fluorescence can be visualized, and the intensity of fluorescence measured, using a fluorescent in vivo microscopy system. Frozen section studies revealed that fluorescein was located in the surface mucous cells and the mucous neck cells. Topically applied ethanol caused a dose-dependent decline in intensity of fluorescence. Measurement of fluorescence in the supernatant bathing the mucosa revealed that leak of fluorescein out of cells or shedding of cells was, at least in part, responsible for the decline in fluorescence intensity. Pretreatment with a "cytoprotective" dose of 16,16-dimethyl prostaglandin E2 did not protect against the decline in fluorescence seen after 12.5% and 25% ethanol. This confirms findings of previous histologic studies that prostaglandin "cytoprotection" does not include surface cell protection. We conclude that this technique provides a sensitive, quantitative in vivo method to study gastric surface cell injury.