Abstract
Zinc metabolism in rat liver was investigated after a single oral administration of zinc sulfate. After the administration of 20 mg Zn per 100 g body weight, the zinc accumulated in the liver and pancreas, but not significantly in the kidneys, heart, spleen or lungs. The amount of zinc excreted into the bile was much less than that accumulated in the liver. On the other hand, the elevation of zinc content in the serum caused a significant increase of zinc in the plasma membrane and the cytosol fractions of the liver cells. However, additional increase of zinc in the serum did not further enhance the elevation of zinc content in the plasma membrane and the cytosol fractions. Upon gel filtration on Sephadex G-75 of the serum and cytosol obtained after zinc administration, the accumulated zinc in the serum was mainly eluted at the void volume, while the metal in the cytosol was largely eluted at 1.8 times the void volume, suggesting that the protein-bound zinc in the serum is not directly transported into the liver cells. The present study suggests that the liver is a target organ of zinc in rats and that zinc taken up by the liver cells is stored by binding of the metal to cytosolic proteins.
