Mechanisms of t-butyl hydroperoxide-induced toxicity to rabbit renal proximal tubules.

This study examined the mechanisms of t-butyl hydroperoxide (TBHP)-induced oxidative injury to a suspension of rabbit renal proximal tubules. TBHP (0.25-1 mM) produced a specific sequence of intracellular events in the tubules. Initially, TBHP increased tubular glutathione disulfide content and lipid peroxidation. Subsequently, there was an increase in ouabain-sensitive oxygen consumption (indicative of an increase in intracellular sodium concentrations), mitochondrial dysfunction, and a decrease in glutathione content. Finally, cell death, as measured by a decrease in tubular retention of lactate dehydrogenase activity, began between 30 and 60 min. The toxicity was dependent on iron-mediated free radical formation, since the iron chelator, deferoxamine, and the antioxidants, promethazine, butylated hydroxytoluene, and dithiotreitol, prevented the lipid peroxidation, the mitochondrial dysfunction, and cell death. Further studies with the antioxidants provided evidence that lipid peroxidation plays an important role in TBHP toxicity in proximal tubules.