The bioinorganic chemistry of Np, Pu and Am in mammalian liver.
Paquet F., Ramounet B., Métivier H., and Taylor D.M.
J. Alloys Compounds 271-273 p85-88
Investigations of the sub-cellular distribution patterns of 239Np and 237Np in rat liver have shown that the distribution of neptunium is time and mass dependent. One hour after administration, 237Np deposits predominantly in the cytosol, whereas at later times after exposure (24 h to 40 days) the nuclei and lysosomes are the main binding sites. In contrast, 24 h after exposure, the 239Np was found mainly in the cytosol. Investigations in baboons with 237Np, 239Pu and 241Am have shown that the cytosol was the main binding site 24 h after exposure, and that nuclei and lysosomes were involved at later times after exposure (10 days). In cytosol, 239Pu and 241Am were bound mainly to ferritin irrespective of the time of sacrifice. For 237Np, it was shown, both in rats and baboons, that the radionuclide binds to two proteins soon after exposure (1-24 h) with molecular weights of 450 and 200 kDa, respectively. The former was identified as ferritin, but the latter remains unidentified. At later times (1-40 days), Np was found to be bound mainly by ferritin and by high-molecular weight compounds.