Multiple effects of presumed glutathione depletors on rabbit proximal tubules

The role of glutathione (GSH) in the protection of normal renal function has been investigated using rabbit proximal tubules. Compounds known to deplete GSH in various biological systems by alkylation (via GSH S-transferases, phorone; 2-cyclohexen-1-one, CHX; diethyl maleate, DEM) or by inhibiting GSH synthesis (buthionine sulfoximine, BSO) were added to suspensions of proxiimal tubules and incubated for 60 min. BSO (1 or 5 mM) did not decrease GSH concentrations, O₂ consumption, or cause lactate dehydrogenase release (LDH). Concentrations of CHX (2 mM) and phorone (10 mM) that decreased GSH concentrations also inhibited O₂ consumption and caused LDH release. DEM (10 mM) did not significantly decrease GSH concentrations but did inhibit oxygen consumption and cause slight LDH release. Time-course studies using CHX (3 mM) showed that GSH levels and O₂ consumption decreased as early as 15 min while LDH release did not occur until 60 min. These results show that: 1) there may be a relationship between O₂ consumption and GSH levels; 2) agents that have been used historically to reduce GSH concentrations have other cytotoxic effects; and 3) rabbit renal proximal tubules appear to be resistant to GSH depletion.