Abstract

2-Br-(diglutathion-S-yl)hydroquinone (2-Br-(diGSyl)HQ) is a potent nephrotoxicant, causing glucosuria, enzymuria, proteinuria, elevations in blood urea nitrogen, and severe histological alterations to renal proximal tubules at doses of 10-15 mumol/kg. In contrast, 2-Br-3-(glutathion-S-yl)hydroquinone (2-Br-3-(GSyl)HQ) is substantially less nephrotoxic than 2-Br-(diGSyl)HQ and requires a dose of at least 50 mumol/kg to cause modest elevations in blood urea nitrogen concentrations. The reason or reasons for this difference in potency is unclear, but since inhibition of renal gamma-glutamyl transpeptidase (gamma-GT) prevents 2-Br-(diGSyl)HQ-mediated nephrotoxicity, metabolism of these conjugates by the kidney must play an important role. To address this question we have compared the metabolism and toxicity of 2-Br-(diGSyl)HQ and 2-Br-3-(GSyl)HQ in the in situ perfused rat kidney (ISPRK). Following infusion of 20 mumol 2-Br-3-(GSyl)HQ into the right renal artery of male Sprague Dawley rats, a total of 23.5 +/- 1.9% (mean +/- SE) of the dose was accounted for in urine and bile over a period of 180 min. 2-Bromo-3-(cystein-S-yl)hydroquinone and 2-bromo-3-(N-acetylcystein-S-yl)hydroquinone were identified in urine, and unchanged 2-Br-3-(GSyl)HQ was identified in urine and bile. The product arising from the oxidative cyclization of 2-bromo-3-(cystein-S-glycine)hydroquinone, 2H-(3-glycine)-7-hydroxy-8-bromo-1,4-benzothiazine, was also identified in urine.(ABSTRACT TRUNCATED AT 250 WORDS)