Influence of iron, deferoxamine and ascorbic acid on gentamicin-induced nephrotoxicity in rats

1. Nephrotoxicity was induced in rats by injecting gentamicin intramuscularly (i.m.) at a dose of 80 mg/kg for 6 days. Treated animals demonstrated a typical pattern of nephrotoxicity characterized by increased serum creatinine and urea concentrations, and by necrosis of proxinal tubular epithelium. 2. Pretreatment of rats with iron (Fe³⁺) at daily i.m. doses of 2, 4 and 8 mg/kg for 14 days, with gentamicin given during the last 6 days of treatment, significantly potentiated the gentamicin-induced increases in creatinine and urea concentrations and exacerbated renal histological damage. 3. Gentamicin significantly increased serum Fe³⁺ concentration in rats treated with Fe³⁺ and gentamicin, compared to Fe³⁺-treated rats. 4. The Fe³⁺ antidote deferoxamine (100 mg/kg, i.m.) given with gentamicin was ineffective in antagonizing the potentiating effect of Fe³⁺ on gentamicine-induced nephrotoxicity. 5. Ascorbic acid (50 mg/kg, i.m. for 14 days) was ineffective in altering the nephrotoxicity of gentamincin (80 mg/kg) given during the last 6 days of treatment. At a dose of 100 mg/kg for 14 days, ascorbic acid significantly reduced gentamicin-induced increases in creatinine and urea levels, and ameliorated proximal tubular damage. However, at a dose of 200 mg/kg, ascorbic acid exacerbated gentamicin-induced increases in creatinine and urea levels and increased the severity of the histological damage.