Alpha-tocopherol protects against the renal damage caused by potassium dichromate

Abstract

Exposure to hexavalent chromium (Cr 6+) causes mutagenic, carcinogenic, and toxic effects, some of which have been associated with its oxidative capacity. In the kidney, Cr 6+ has been claimed to provoke necrosis of the proximal tubular cells. Our aim was to assess the functional involvement of the different segments that form the nephron in a model of acute renal failure caused by potassium dichromate and the participation of oxidative damage in this process. We also studied the possible protective effect of α-tocopherol (α-TOC) against renal damage. Wistar female rats 200 g body weight (bw) received potassium dichromate (15 mg/kg, sc, single dose). Lipid peroxidation and renal function were evaluated on days 0, 1, 2, 3, 7, 10, and 14. A second group received α-TOC (125 mg/kg, by gavage) 5 days before and during dichromate exposure (same dose as for the first group), and was monitored at 0, 2, and 7 days of exposure. Creatinine clearance, glucose and sodium fractional excretions, p-aminohippurate uptake, free-water and osmolal clearances were also measured. Thiobarbituric acid-reactive substances were quantified in renal cortex. The results revealed altered proximal tubule function, decreased glomerular filtration, and distal segment dysfunction, accompanied by oxidative damage 48 h after exposure to dichromate. In the α-TOC-treated group proximal reabsorptive and secretory functions were preserved, suggesting that oxidative damage is a participating mechanism in dichromate toxicity on these functions. In contrast α-TOC did not prevent glomerular or distal dysfunction, indicating selectivity of the protection afforded by this compound on the toxicity of dichromate, at the several components of the nephron.