Comparative tissue uptake and cellular deposition of three different plutonium chemical forms in rats

To evaluate the influence of the chemical form of plutonium (Pu) on its distribution in tissues and within liver cells populations.

Groups of male Sprague-Dawley rats were contaminated by intravenous injection of either Pu citrate, Pu nitrate or Pu phytate. Pu content was determined in various tissues at different times after injection. Pu liver distribution was analysed by autoradiography and after cellular separation.

Biokinetic studies indicate that Pu citrate and Pu nitrate predominantly retained in the skeleton within the first hours after injection, whereas most of the Pu was in the liver after injection of Pu phytate. Autoradiographs showed that Pu citrate was homogeneously distributed in the liver, while Pu nitrate accumulated into 'hot points'. Pu phytate showed an intermediate distribution pattern. Hepatic cell separation revealed a difference of uptake between the two cell types depending on the chemical form of injected Pu, and on the time after contamination.

Distinct Pu behaviour was observed for biokinetics, retention and liver distribution. The large differences noted between citrate, nitrate and phytate might be explained by differences in systemic and hepatic transport.