Metabolism of Zinc-65 in Man

Abstract

After a single intravenous injection of Zn65 chloride in man the level of Zn65 in plasma decreased rapidly, while the concentration of Zn65 in whole blood remained high. The ratio of Zn65 in whole blood to that of plasma was 3:1 at 24 hours and increased in the subsequent 4 weeks. The main pathway of Zn"5 excretion was via the intestine. The whole-body retention of Zn65 determined in 2 patients with the whole-body counter could be described by the sum of 2 exponential functions. The average biological half-life of the smaller compartment was 12.5 days, and the turnover rate of the larger compartment averaged 322 days. Uptake of Zn65 was highest in liver, kidney, and spleen; these concentrations decreased with time. The uptake of Zn65 in tissues of glandular organs, including the pancreas and prostate, was relativley high, but lower than in liver and kidney. Distinct differences in Zn65 uptake were observed in different types of skeletal muscle. The Zn65 concentration in large and small intestine was also relatively high.