EFFECT OF REACTIVE OXYGEN SPECIES ON ENDOTHELIN-1 PRODUCTION BY HUMANMESANGIAL CELLS

Reactive oxygen species (ROS) have been implicated in the pathophysiol ogy of renal ischemia/reperfusion injury. Endothelin-1 (ET-1) is gener ated in abundance in renal ischemia/reperfusion with resultant decreas es in renal blood how and glomerular filtration rate. To determine if ROS regulate ET-1 production, the effect of ROS donors or scavengers o n ET-1 protein and mRNA levels in cultured human mesangial cells was e xamined. Incubation with xanthine/xanthine oxidase, glucose oxidase, o r H2O2 caused a dose-dependent rise in ET-1 release. Similarly, xanthi ne/xanthine oxidase or H2O2 augmented ET-1 mRNA levels. In contrast, t he ROS scavengers dimethylthiourea (DMTU), dimethylpyrroline N-oxide, or pyrrolidine dithiocarbamate reduced basal ET-1 release, while DMTU lowered ET-1 mRNA levels. Deferoxamine, an iron chelator, also decreas ed basal ET-1 release. Superoxide dismutase potentiated the ET-1 stimu latory effect of xanthine/xanthine oxidase, while catalase abrogated t he effect of xanthine/xanthine oxidase and H2O2. The effects of ROS we re unrelated to changes in nitric oxide production or cytotoxicity. Th ese data indicate that exogenously or endogenously-derived ROS can inc rease ET-1 production by human mesangial cells. While superoxide anion reduces ET-1 levels, H2O2 leads to enhanced production of the peptide . ROS stimulation of mesangial cell ET-1 production may contribute to impaired glomerular hemodynamics in the setting of renal ischemia/repe rfusion injury.