PROSTAGLANDIN E(2) SYNTHESIS AFTER OXIDANT STRESS IS DEPENDENT ON CELL GLUTATHIONE CONTENT

The role of glutathione in protecting prostaglandin (PG) generation af ter exposure of fibroblasts to oxidant stress was investigated. Exposu re of 3T3 fibroblasts to H2O2, followed by washing and then 20 mu M ar achidonic acid, caused a dose-dependent decrease in PG synthesis as as sessed by radioimmunoassay. PGE(2) production decreased from 3.7 +/- 1 .1 to 0.15 +/- 0.04 pmol/mu g protein, and prostacyclin (PGI(2)) forma tion decreased from 0.56 +/- 0.03 to 0.06 +/- 0.03 pmol/mu g protein a fter exposure to 200 mu M H2O2 Decreasing intracellular glutathione wi th 50 mu g/ml 1,3-bis(chloroethyl)-1-nitrosourea (BCNU) enhanced the H 2O2-induced decrease in PGE(2) synthesis. Another glutathione-depletin g agent, 1-chloro-2,4-dinitrobenzene (CDNB), also potentiated the H2O2 -induced decrease in PGE(2) formation. However, although PGI(2) produc tion was decreased by H2O2, neither BCNU nor CDNB potentiated this dec rease. Without oxidant stress, extreme glutathione depletion decreased PGE(2) synthesis and caused PGI(2) synthesis to exceed PGE(2). In sum mary, oxidant stress decreases both PGE(2) and PGI(2) formation. Howev er, the primary effect of decreasing cell glutathione during oxidant s tress is a reduction in PGE(2) formation, not PGI(2). This implies tha t the predominant effect of glutathione depletion during oxidant stres s is on the PGE(2) isomerase(s) and not PGH synthase or PGI(2) synthas e.