The effect of copper on zinc in liver and in metallothionein

The question as to the increase in zinc content in metallothionein in response to copper injection was examined. Each rat was injected intraperitoneally once with 0.9% NaCl or copper (2, 4 or 6 mg copper/kg b.w.). After copper injection, 54.0-62.9% of the hepatic zinc contents were found in the cytosol. Although the zinc contents in the cytosol and livers of copper-injected rats were higher than those of control rats, they did not increase in response to copper injection. The distribution profiles of the hepatic cytosol of copper-injected rats on a Sephadex G-75 column showed that the amount of the increased zinc was attributable to the metallothionein and high molecular weight protein fractions. Although the zinc contents in hepatic metallothionein of copper-injected rats were higher than those of control rats, they did not increase in response to copper injection. These results indicate that zinc contents in liver and in metallothionein did not increase in response to copper injection.