Protective role of intracellular glutathione against nitric oxide-induced necrosis in rat gastric mucosal cells

Background: Nitric oxide synthase activity is increased in the stomach in a ssociation with Helicobacter pylori infection and portal hypertension, but the mechanism by which nitric oxide contributes to mucosal damage remains u nclear. Aim: To examine whether nitric oxide injures gastric mucosal cells and whet her cellular glutathione affects nitric oxide-induced cytotoxicity. Methods: A confluent monolayer of RGM-1 gastric mucosal cells was exposed t o nitric oxide donors (NOC5 or NOC12). Cell viability was determined by try pan blue dye exclusion, lactate dehydrogenase release and supravital staini ng with Hoechst 33342 and propidium iodide. The kinetics of the reduced/oxi dized forms of glutathione were also measured, as well as the effect of glu tathione-depletion or glutathione-precursor induced cytotoxicity. Results: Excess exogenous nitric oxide produced by NOC5 or NOC12 induced ne crosis in RGM-1 cells in a time- and concentration-dependent manner. The le vel of reduced glutathione drastically decreased prior to the loss of cell viability and remained low, but oxidized glutathione was not affected. Glut athione depletion increased necrosis of both NOCs in an NOC-concentration-r elated fashion, while pre-treatment with gamma-glutamylcysteine ethyl ester reduced their necrotic susceptibility. Conclusion: Exogenous nitric oxide induced necrosis in gastric mucosal cell s, and intracellular reduced glutathione protects gastric mucosal cells fro m damage by nitric oxide.