Effect of cadmium in the zinc deficient rat.

Three-w-old male Sprague-Dawley rats were given a zinc (Zn)-deficient (0 ppm Zn) or a Zn-adequate diet (30 ppm Zn) supplemented with 0, 0.5 or 100 ppm cadmium (Cd) for up to 5 mo. The proximal convoluted tubules of the kidneys had degenerative changes in the rats fed the Zn-deficient diet containing 100 ppm Cd [Zn 0, Cd 100], but there were no lesions in other groups. Electron microscopy showed cytoplasmic vacuolation of the proximal tubules, mitochondrial swelling and coagulative necrosis in Zn 0:Cd 100 rats. The present study revealed diminished bone growth and cortical thinning of the femur, but there was no osteomalacia seen in Itai-Itai disease patients. The results indicate that Zn deficiency may enhance the renal toxicity of Cd, but that dietary Cd did not cause osteomalacia even under severe Zn-deficient conditions.