Effect of mild iron overload on liver and kidney lipid peroxidation

RESUMO

1. Hepatotoxicity is the most common finding in patients with iron overload since the liver is the major recipient of iron excess, even though the kidney could be a target of iron toxicity. The effect of iron overload was studied in the early stages after iron-dextran injection inrats, as a model for secondary hemocromatosis. 2. Total hepatic and kidney iron content was markedly over control values 20h after the iron administration. Plasma GOT, GPT and LDH activities were not affected, suggesting that liver cell permeability was not affected by necrosis. 3. Spontaneous liver chemiluminescence was measured as an indicator of oxidative stress and lipid peroxidation. Light emission was increased four-fold 6 h after iron supplementation. 4. Increases in the generation of thiobarbituric acid reactive substances (TBARS) in liver and kidney homogenates were detected after iron administration. 5. The activities of catalase, SOD and glutathione peroxidase were determined. Enzymatic activities declined in liver homogenates by 25, 36 and 32 por cento, respectively, 20 h after iron injection. These activities were not affected in kidney as compared to control values, except for SOD activity that was decreased by 26 por cento. 6. The content of alfa-tocopherol was decreased by 31 por cento in whole kidney homogenates and by 40 por cento in plasma. 7. Our data indicate that lipid peroxidation occurs after mild iron overload both in liver and kidney. Enzymatic antioxidantes are consumed significantly in liver and alfa-tocopherol content decreases in kidney, suggesting an organ-specific antioxidant effect