Effects of Vitamin E on Renal Dysfunction in Chronic Cadmium-Poisoned Rats

Abstract

Cadmium is a highly toxic metal that can be ingested or inhaled from a variety of industrial and dietary sources. The purpose of this study was to investigate the effects of vitamin E on renal dysfunction and blood pressure changes in chronic cadmium-poisoned rats. Sprague-Dawley rats weighing 100 ± 10 g were randomly assigned to one control group and three cadmium-poisoned groups. Cadmium groups were assigned to dietary groups according to levels of vitamin E supplementation: vitamin E-free diet (Cd-0E group), 40 mg of vitamin E/kg of diet (Cd-40E group), and 400 mg of vitamin E/kg of diet (Cd-400E group). The animals were raised for 20 weeks, and cadmium was supplied in the drinking water at 50 ppm Cd²⁺. The morphological changes observed by both light and electron microscopy revealed mitochondria and tubule epithelial cell edema in the Cd-0E group, yet this was alleviated with the highest level of vitamin E supplementation (Cd-400E group). The urinary β₂-microglobulin levels indicated that glomerular injury was higher in the Cd-poisoned groups than in the control group, but were lowered by vitamin E supplementation. Although the glomerular filtration rate (GFR) of the Cd-0E group was significantly lower than that of the control group, the vitamin E-supplemented groups exhibited a similar GFR to the control group, suggesting that vitamin E protected the kidney from functional damage. Angiotensin converting enzyme activity, and blood pressure, and heart rate were all significantly higher in the Cd-poisoned group, but each remained nearly normal with vitamin E supplementation. Accordingly, these results indicate that vitamin E supplementation in chronic cadmium-poisoned rats normalized renal dysfunction and blood pressure regulation.