Microscopic and Autoradiographic Studies of Distribution of Uranium in the Rat Kidney

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Abstract
The distribution of uranium in rat kidney has been studied by autoradiography and the data compared with that found by radiochemical analysis in order to obtain more information relating to the phenomenon of prolonged retention of uranium by kidneys of rats given an intravenous injection of a large mass of uranium. Dose levels of 10 μg U/kg, 100 μg U/kg and 1000 μg U/kg were used. These experiments indicate that retention is significantly higher at the two higher levels than at the lowest level. A concentration ratio, the ratio of the average concentration in the cortex to the average concentration in the entire kidney, was approximately 1.3. At early times post-injection the uranium tracks were observed mainly in proximal tubules, but an increasing proportion of total tracks was in distal tubules as post-injection time increased. Leaching and redistribution of uranium, in the processes of preparation, appeared to be negligible. There were indications of a gradient in the cortex when aggregates were counted, but with aggregates excluded the concentrations were similar throughout the cortex. Proximal tubules of damaged kidneys did not show a change in diameter from those of normal kidneys, but glomeruli in injected rats tended to be smaller than in uninjected rats. Histopathological changes up to 28 days post-injection were striking at high dose levels.