Uranium microlocalization in renal proximal tubules of rats during initial phase of exposure to uranyl acetate

抄録

The kidney is the primary site of uranium (U) deposition after exposure. The distal portion—S3 segment of the proximal tubules may be involved in U reabsorption from the urine. However, the dynamics of the U distribution in renal tubules have not yet been clearly understood. This study precisely examined the distribution of U within the S3 segment (S3 tubules) in male Wistar rats during the initial phase (1–3 h) of subcutaneous administration with uranyl acetate (UA), 0.5 mg/kg of body weight. X-ray fluorescence spectrometry with a high-energy synchrotron radiation microbeam (SR-μXRF) was employed. At 1 h of administration, U was rapidly transported into the kidneys and accumulated at 4% of the dose. A cross-section of the S3 tubules revealed a distribution of U within the brush border, indicating that U reabsorption was in-progress at this time point. Enhanced U accumulation with a maximum of 134 μg/g was also detected in the epithelium of the S3 tubule microregions. At 3 h, U accumulation in the kidneys was 9%, and U microlocalization in the S3 tubule epithelium reached approximately 200 μg/g. These microlocalization distribution patterns were characteristic of U and differed from those of endogenous trace elements, such as iron and zinc. These findings are valuable for designing decorporation strategies applicable to the U accumulated in this critical organ.