Combination of micro-PIXE and SR-XRF for elemental distribution in the small intestine of mice administered with CsCl

The small intestine is important for the absorption of orally ingested substances. The luminal surface of the intestinal tract is covered with the villi, which is responsible for initial absorption. However, the elemental distribution in the fine structure of the intestine has not been clearly understood. Particle-induced X-ray emission analysis with microbeam (micro-PIXE) detects light elements and is suitable for the elemental distribution analysis of biological tissues. Conversely, synchrotron radiation X-ray fluorescence (SR-XRF) predominantly detects heavy metals. Herein, the intestinal elemental distribution was examined in mice administered with Cs by combining micro-PIXE analysis for endogenous P, K, and S and SR-XRF analysis using high-energy synchrotron radiation for Cs. Elemental distributions corresponding to the luminal structure were obtained using sections of the small intestine; P, K, and S concentrations were higher in the villi than in the basal region in the intestine of the control mice. Cs administration did not considerably alter the distributions of these elements. Additionally, Cs was higher in the villi than in the basal region of the intestine and was found at the center area of the villi where the lamina propria and capillary vessels of circulation are distributed, with high magnification analysis. The proposed method is useful for studying the intestinal dynamics of Cs distribution.