ZINC-BINDING PROTEIN IN LIVERS OF NEONATAL, NORMAL AND PARTIALLY HEPATECTOMIZED RATS

In the livers of rat after partial hepatectomy the zinc concentration began to increase soon after the operation, reached a maximum value at 14h, and decreased to the original value by 25h after the operation. In contrast, the plasma zinc concentration continued to decrease during the first 10h after the operation and remained depressed for at least 28h. The plasma and hepatic zinc concentrations were relatively unaffected by sham-operation. Synchronous with the increase in the hepatic zinc concentration after the partial hepatectomy, there was an appearance of zinc-binding protein (Zn-binding protein) in the liver cytosol. Studies with small doses of actinomycin D and cycloheximide suggest that both RNA and protein syntheses are necessary for the induction of Zn-binding protein after partial hepatectomy. A high content of the Zn-binding protein was found in neonatal rat liver. The Zn-binding protein, however, was undetectable 40 days after birth. The Zn-binding protein was also found in the adult rat liver when stimulated to proliferate after the administration of isoprenaline followed by glucagon. These findings indicate a close linkage between the appearance of Zn-binding protein in the liver cytosol and the regulation of DNA synthesis.