Phosphorus and potassium distributions in the kidneys of mice administered with renal tubular invasion heavy metals by micro-PIXE

The kidney is crucial for the disposition of heavy metals taken into the body, and the renal proximal tubules are responsible for the region-specific reabsorption of substances from the urine. However, the dynamics of the elemental distributions in the renal tubules have not been clearly understood. Herein, the precise distributions of endogenous elements, such as P and K in the kidney with distinct tubular regions, were examined in mice administered with renal tubular invasion heavy metals, such as Pt or Cd, by particle-induced X-ray emission analysis with microbeam (micro-PIXE). Renal cryosections (thickness = 10 μm) were subjected to micro-PIXE analysis. Areas with concentrated P and K were observed in the outer stripes of the outer medulla, in which the distal portion of the proximal tubules was distributed after the administration of Cd but not Pt. Additionally, the dynamics of the Pt and Cd distributions were examined by high-energy X-ray fluorescence (SR-XRF) analysis using high-energy synchrotron radiation utilizing serial sections of micro-PIXE specimens. Cd was distributed mainly in the cortex, where the proximal portion of the proximal tubules were distributed, early after administration, but later spread to the outer stripe of the outer medulla, where the distal portion of the proximal tubules was distributed. Pt was uniformly distributed in the renal tubular regions. The combined micro-PIXE and SR-XRF techniques can robustly study the element distribution dynamics in renal tubules.