AJP - Renal Physiology, Vol 259, Issue 2 338-F347, Copyright © 1990 by American Physiological Society
Oxidative stress in isolated rat renal proximal and distal tubular cells
L. H. Lash and J. J. Tokarz
Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan 48201.
Suspensions of purified proximal tubular (PT) and distal tubular (DT) cells
were isolated from rat kidney cortical cells by Percoll density-gradient
centrifugation and were used to investigate susceptibility of these regions
of the nephron to oxidative injury. Exposure to tert-butyl hydroperoxide
(tBH), menadione (MD), or H2O2 produced significantly greater cytotoxicity,
as assessed by leakage of lactate dehydrogenase, in DT cells than in PT
cells. The order of cytotoxic potency in both cell types was MD greater
than tBH greater than H2O2. Preincubation of PT and DT cells with 5 mM
glutathione (GSH) or 5 mM dithiothreitol delayed tBH-induced cytotoxicity,
indicating a protective role of GSH. Addition of buthionine sulfoximine and
acivicin with GSH, to inhibit GSH synthesis and degradation, eliminated the
protective effect of GSH, indicating that protection by GSH in DT cells is
not dependent on uptake of the intact tripeptide. Incubation of both PT and
DT cells with tBH resulted in oxidation of GSH to glutathione disulfide.
Activities of five detoxication enzymes were significantly higher in PT
cells, indicating that a diminished ability to detoxify reactive
metabolites may contribute to the higher intrinsic susceptibility of DT
cells to oxidative injury.
