The Binding of Polonium-210 to Rat Tissues

LANZOLA, E. E., ALLEGRINI, M. E., AND TAYLOR, D. M. The Binding of Polonium-210 to Rat Tissues. Radiat. Res. 56, 370-384 (1973). The subcellular distribution of 210Po has been studied over periods of up to 47 days after intravenous, oral or intramuscular injection of the nuclide as citrate or in colloidal form. The majority, 50 to 80%, of the total tissue 210po was found in the cytosol of liver, kidney and testis irrespective of the time after injection, the route or form in which the nuclide was administered. Fractionation of the cytosol on Sephadex G.200 suggested that the 2l0po was bound nonspecifically to protein. Studies of the distribution of 210Po in digests of freeze-dried liver from animals injected with 210Po and in synthetic mixtures of amino acids after separation on Sephadex G.15 suggest that the sulphydryl group of cysteine may be an important binding site for 2l'Po in proteins. Slight changes in the 21OPo distribution profile were seen when lipid was extracted from the freeze-dried liver powder before digestion suggesting that lipids may be involved in the 21OPo complex in vivo, but no direct evidence for polonium-lipid complexes was found.