Differential Role of Reactive Oxygen Species in Chemical Hypoxia-Induced Cell Injury in Opossum Kidney Cells and Rabbit Renal Cortical Slices

Abstract

This study was undertaken to evaluate the role of reactive oxygen species (ROS) and lipid peroxidation in chemical hypoxia in opossum kidney (OK) cells and rabbit renal cortical slices. Chemical hypoxia was induced by incubating cells or slices with antimycin A, an inhibitor of mitochondrial electron transport. Exposure of OK cells to chemical hypoxia resulted in a time-dependent cell death and parallel depletion of intracellular ATP. In OK cells subjected to chemical hypoxia, the generation of ROS was increased, and this was prevented by the H₂O₂ scavenger catalase, but not by the hydroxyl radical scavenger dimethylthiourea (DMTU). Catalase prevented OK cell death induced by chemical hypoxia, but [Cu, Zn]-superoxide dismutase (SOD) and DMTU were not effective. The iron chelators deferoxamine and phenanthroline prevented chemical hypoxia-induced OK cell death, but the potent antioxidants N,N′-diphenyl- p-phenylenediamine (DPPD) and butylated hydroxyanisole (BHA) showed no beneficial effect. Antimycin A in OK cells increased lipid peroxidation, which was prevented by DPPD and phenanthroline. In rabbit renal cortical slices, antimycin A caused an increase in LDH release and lipid peroxidation, and these effects were prevented by ROS scavengers (SOD, catalase, and DMTU), iron chelator (deferoxamine), and antioxidants (DPPD and BHA). However, in primary cultured rabbit proximal tubular cells the antimycin A-induced cell death was not altered by antioxidants. The extent of ATP depletion was similar in renal cortical slices and primary cultured cells treated with antimycin A. These results indicate that chemical hypoxia-induced cell injury is not directly resulted from lipid peroxidation in OK cells, but this cell injury is mediated by lipid peroxidation in rabbit renal cortical slices. This discrepancy may be due to the difference in cell preparation (freshly prepared tubules and cultured cells).