Prostaglandins protect gastric mucosa against noxious agents, but it is unknown whether this protection includes a direct action on the cells themselves, this action is limited to damaging agents that inhibit prostaglandin synthesis, or cellular cyclic adenosine monophosphate is the mediator. The present study tested these questions in cultured gastric mucous epithelial cells. The effect of 16,16-dimethyl prostaglandin E2 on cellular cyclic adenosine monophosphate level and the effect of 16,16-dimethyl prostaglandin E2, dibutyryl cyclic adenosine monophosphate, and isobutyl methyl xanthine on taurocholate-induced damage to cultured rat gastric mucosal cells was determined. As parameters of cell damage, the trypan blue dye exclusion test and 51Cr-release were employed. Taurocholate significantly increased 51Cr-release in a dose-dependent manner and decreased the number of viable cells. 16,16-Dimethyl prostaglandin E2 (1.0 microM) diminished the cell damage caused by 10 mM taurocholate (p less than 0.01) and increased cyclic adenosine monophosphate levels. Prostaglandin F2 alpha but not prostaglandin I2 was also cytoprotective. Addition of dibutyryl cyclic adenosine monophosphate (1.0 mM) and isobutyl methyl xanthine while significantly increasing cyclic adenosine monophosphate levels did not significantly reduce taurocholate-induced cell damage. Thus, in vitro 16,16-dimethyl prostaglandin E2 directly protects gastric mucous cells against taurocholate-induced injury, direct prostaglandin cytoprotection is not limited to damaging agents that inhibit prostaglandin synthesis, and cyclic adenosine monophosphate levels do not correlate with gastric mucosal cell damage and may not be involved in the direct protective effect of prostaglandins.