To investigate the mechanism of cis-diamminedichloroplatinum(II) (cisplatin) nephrotoxicity, male Sprague-Dawley rats were given one injection of cisplatin (6 mg/kg i.v.). Urinary levels of amino acids and gamma-glutamyl transpeptidase were monitored for 8 days; kidney homogenate content of gamma-glutamyl transpeptidase was followed for 50 hr, and that of selenium-dependent glutathione peroxidase and total glutathione was followed for 4 hr. Peak urinary levels of amino acids and gamma-glutamyl transpeptidase occurred 4.5 hr after the i.v. dose. Glutamine, glycine, and ethanolamine were all elevated greater than 20 times that of the control at 4.5 hr and were still significantly elevated at 50 hr. Total renal glutathione content increased 51 +/- 17% (S.D.) of control values 20 min after cisplatin was given, before returning to base-line levels. No depletion of either renal glutathione or glutathione peroxidase was detected over the time interval studied. These results demonstrate an earlier physiological impairment than has hitherto been shown. Furthermore, depletion of glutathione and glutathione peroxidase does not occur in the rat kidney following therapeutic doses of cisplatin, in contrast to the changes observed in cardiac tissue following doxorubicin treatment.