Distribution and Excretion of Three Chemical Species of 239Pu(IV) in the Beagle

Abstract

The early retention and distribution of 239Pu in the beagle were compared following intravenous administration of 239Pu(IV) as the transferrin complex (Pu-Tf), as a plutonium complex in citrate buffer (Pu-Cit) of pH 3.5 and as a particulate Pu(IV) in colloidal form (Pu-P). The early distribution and retention of Pu(IV) at 14 days after injection of Pu-citrate and pu-transferrin were indistinguishable. There was a difference in urinary excretion patterns. Deposition, microdistribution and retention after administration of a suspension of particulate Pu(IV) differed greatly from those seen in dogs injected with true solutions of plutonium. After injection of Pu-Tf or Pu-Cit, the nuclide was cleared from circulation at a slow rate. Approximately 30% was deposited in the liver, ∼50% in the skeleton and ∼2% in other soft tissues. Pu-P left the circulation at a very fast rate, ∼70% was deposited in the liver, with only 2% in the bone and ∼24% in other soft tissue. Only an insignificant fraction of the injected Pu-P was excreted. In the liver, the microdistribution after injection of Pu-Tf and Pu-Cit was uniform and Pu(IV) was associated first with soluble protein and later transferred to subcellular liver particles. After injection of Pu-P the microdistribution was heterogeneous; most of the Pu(IV) was located in R. E. cells and little was associated with soluble proteins. After injection of Pu-Cit and Pu-Tf, Pu(IV) was found on bone surfaces, whereas after injection of Pu-P, the small amount of Pu(IV) present was located exclusively in macrophages of the bone marrow.