Turnover of parenterally administered zinc and cadmium and the redistribution of metallothionein bound zinc in newborn rats.
The whole body retention, tissue distribution and protein binding patterns of 65Zn were compared with 109Cd in newborn rats during postnatal development. One-day-old pups received a single injection of either 65Zn (2.5 microCi) or 109Cd (2.5 microCi plus 1 mg Cd/kg as CdCl2). During the 22 days of age, the whole body retention of 109Cd was higher than that for 65Zn. The biological half times were 466 and 46.3 days for 109Cd and 65Zn, respectively. There were marked differences in tissue deposition of these metals. Both liver and kidney accumulated more 109Cd than other tissues while the 65Zn showed a uniform distribution, with a gradual decrease in radioactivity with age. At the time of weaning, 109Cd had accumulated mainly in liver and kidney whereas, 65Zn was found predominantly in bone and skin. The specific binding of 109Cd to hepatic MT in newborn rats did not change with growth. Although a significant amount of 65Zn initially accumulated in the MT fractions in the liver, it was transferred gradually to high molecular weight protein fractions during development. The administration of these 2 metals had no effect on the body weight, liver weight and total hepatic zinc concentration. However, a significantly high content of MT and zinc in MT fractions was detected in the livers of Cd-treated rats at 22 days of age. The results show the transfer of the essential metal, zinc from hepatic MT to other proteins and the specific binding of cadmium, the non-essential metal to MT during postnatal development in rats.
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D001822:Body Burden; D002104:Cadmium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008668:Metallothionein / Q000378:metabolism*; D008970:Molecular Weight; D011485:Protein Binding; D011868:Radioisotopes; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution; D015032:Zinc / Q000378:metabolism*; D015037:Zinc Radioisotopes
D011868:Radioisotopes; D015037:Zinc Radioisotopes; D002104:Cadmium; D008668:Metallothionein; D015032:Zinc