THE DEPOSITION OF URANIUM IN BONE

Abstract

Distributionand excretion studies (l-4) have consistently revealed that a large proportion of parenterally administered uranium is deposited in the skeleton from which it is mobilized slowly.It appeared advisable, therefore, to investigate the extent and nature of the affinity of the bone substances for uranium under the more controlled conditions obtainable with preparations in vitro.Bone ash and fresh bone were equilibrated with uranium in a bicarbonate buffer under a variety of conditions, especially those considered to simulate conditions existing in the animal during uranium poisoning.In all cases, a transfer of uranium from the solution to the bone phase was observed.Simultaneously, there was an increase in the amount of calcium dissolved by the buffer.These findings suggested that the mechanism of fixation of uranium involves an ionic exchange with some group (probably calcium) on the surface of the mineral phase.Studies of the solubility of uranium in the solutions employed substantiated the ion exchange hypothesis.No precipitation of uranium (as neutral phosphates) occurred in the range of concentrations of physiological interest.