Recovery of cellular functions following oxidant injury

This study investigated the recovery of renal proximal tubule cellular (RPTC) functions following oxidant-induced sublethal injury. tert- Butylhydroperoxide (TBHP) treatment resulted in 24% cell death and loss 4 h following the exposure. The remaining sublethally injured RPTC proliferated, and monolayer DNA content returned to control values on day 4 following TBHP exposure. Basal oxygen consumption (QO₂) and ATP content in sublethally injured RPTC were decreased 64 and 63%, respectively, at 4 h and returned to control values on day 6. Net lactate consumption decreased 71% at 4 h and returned to control values on day 4. In contrast, net glutamine consumption increased 2.7-fold at 4 h and returned to control values on day 6. Ouabain- sensitive QO₂, Na⁺-K⁺-adenosinetriphosphatase (Na⁺-K⁺-ATPase) activity, and Na⁺-coupled glucose transport were inhibited 77, 88, and 83%, respectively, at 4 h and recovered to control values on day 6. These data show that 1) mitochondrial function, Na⁺-K⁺-ATPase activity, active Na⁺ transport, and Na⁺-coupled glucose transport are decreased in sublethally injured RPTC following oxidant exposure and are repaired over time; 2) monolayer regeneration precedes the recovery of mitochondrial and transport functions, and 3) sublethal injury and subsequent regeneration are associated with alterations in metabolic substrate utilization. These results suggest that oxidant-induced sublethal injury to RPTC may contribute to renal dysfunction and that RPTC can repair and regain cellular functions following oxidant injury.