Effects of Radiation on Zinc Metabolism of Sheep

Abstract

SASSER, L. B., BELL, M. C., WADE, L., JR., AND JARBOE, G. E. Effects of Radiation on Zinc Metabolism in Sheep. Radiat. Res. 46, 115-128 (1971). Erythrocytes from 64 sheep given either a single gamma exposure to the whole body (240 R), a single beta dose to the skin (57 krads), an ingested dose of 90Y-labeled sand (2.4 mCi/kg body weight), or combinations of these three treatments were incubated with 65Zn and the percentage erythrocytic 65Zn uptake was determined. Concentrations of stable zinc in plasma and erythrocytes were also measured. In vitro uptake of 65Zn by erythrocytes of gastrointestinal and skin-irradiated sheep was higher than that of control sheep, but stable Zn content of erythrocytes was unaffected. Plasma Zn concentration was decreased (P < 0.05) by skin irradiation, but not by gastrointestinal or whole-body irradiation. Five skin-irradiated and two control sheep were intravenously dosed with 65Zn one year after irradiation and the turnover rate of Zn and tissue distribution of 65Zn were measured. The turnover rate of Zn in plasma was 4.8 mg/day per kilogram in skin-irradiated sheep and 6.9 mg/day per kilogram in control sheep. Urinary excretion of 65Zn by skin-irradiated sheep was increased, while fecal 65Zn was reduced the first day but unchanged over the total 10-day collection period. The injury produced by the radiation was probably responsible for the increased uptake of 65Zn by the erythrocytes rather than a direct effect of radiation to the erythrocyte or change in dietary Zn levels. The injury may have caused a shift of plasma proteins (a higher fraction of globulins) affecting the availability of Zn to the erythrocyte or caused