The biosynthesis of metallothionein rat liver and kidney after administration of cadmium

Abstract

The biosynthesis of the cadmium-binding protein, metallothionein, was studied in rat liver and kidney after injection of cadmium chloride. A simplified procedure for the isolation of metallothionein from liver and kidney tissues was devised. It was found that the concentration of a subcutaneously injected dose of 30 mumoles of 109CdCl2/kg in the liver reached the maximum within 36 h. Thereafter, a slow decrease in the concentration of the isotope was noted during the 3 week period. In the kidney, the isotope was taken up in two phases. During the first phase the uptake was faster and lasted for about 4 days. The second phase of 109Cd accumulation showed a slower increase in the concentration oe 109Cd was associated with metallothionein. Amino acid incorporation studies revealed that active biosynthesis of metallothionein took place in the kidney as well as in the liver of cadmium-exposed rats. The turnover of 35S-labeled metallothionein was also investigated and the half-lives of the hepatic and the renal metallothionein were found to be 2.8 and 5 days, respectively.