[The effects of zinc on cadmium-induced ultrastructural changes in rat livers (author's transl)].

The superimposed effects of oral zinc administration on cadmium-induced ultrastructural changes in rat livers were studied. Twenty female rats were divided into 4 groups. To the diet for group I was added 200 ppm Cd for daily about 10 g diet, to that for group II 200 ppm of Zn and that for group III 200 ppm of Cd and Zn each. The group IV was the control. All of the four groups was sacrificed after 9 months of administration. In addition to examine the liver by an electron-microscope, Cd concentration in the liver was analyzed by atomic absorption spectrophotometry. The Cd contents in the livers of group III were significantly reduced compared with those of group I. Apparent ultrastructural changes; i.e., deterioration of rough endoplasmic reticula, losses of glycogen particles, and proliferation of smooth endoplasmic reticula, were observed in the livers of group I. Meanwhile, these changes were significantly mild in those of group III. From these results, it is suggested that Cd inhibits protein synthesis and glycogen metabolism in the liver and that Zn partly protects the liver from Cd-induced ultrastructural changes.