Assessment of the possible role of iron and copper in cisplatin-induced nephrotoxicity in the rat.

Nephrotoxic lesions induced by cisplatin in rats are characterized by acute tubular necrosis in the outer stripe of the medulla. The purpose of this study was to examine the potential role of changes in metal binding proteins, and iron and copper content in urine and renal tissue in cisplatin-induced nephrotoxicity. Cisplatin was administered intravenously to groups of 20 rats at single doses of 0, 1, 2.5, and 5 mg/kg and rats were sacrificed at 1, 2, 3 and 6 days after treatment. Increased serum BUN and creatinine were observed at a dose of 5 mg/kg cisplatin on day 2 through day 6. Increased urinary copper excretion coincided with necrosis and increased BUN and creatinine on day 3 in the high-dose group. Evidence of renal injury was apparent histologically as karyomegaly at all dose levels as early as 48 hours after injection of cisplatin, prior to increases in urinary copper levels. No change in the distribution of metal binding proteins (transferrin, ferritin, ceruloplasmin, and metallothionein) evaluated by immunohistochemical staining, was seen. Based upon these results, it is unlikely that changes in metal excretion play a primary role in cisplatin-induced nephrotoxicity however, changes in nuclear function indicated by karyomegaly may be involved in early renal injury.