Complete analysis of the trace elements of the kidney

Publisher Website
Google Scholar
Abstract
The distribution of trace elements in kidney cortex and medulla and in their subcellular fractions was studied by inductively coupled plasma mass spectrometry (ICP-MS). This technology allows the analysis of almost all the elements of the periodic table, along with their isotopes, in the same experiment. Acid digestion of the tissue (samples) was required before ICP-MS elemental analysis. Mineralization in 8 N nitric acid for 2 min in a Parr microwave acid digestion bomb, inside a regular microwave oven working at medium power, gave good sensitivity and reproducible results. Trace element determinations could be precisely performed, despite the presence of a considerable amount of organic matter. Cortex/plasma and medulla/plasma inorganic ratios were taken as indicators of the inorganic bioaccumulation. The highest enrichment factors of elements found in the cortex were Mn > Co > Tl > Zn > Rb > Mo > Cu and the highest element enrichments of the medulla were Tl > Mn > Co > Rb > Zn > Bi > Mo > Ni > Cu. Subcellular fragmentation of the kidney cortex and medulla indicated that the majority of the trace elements was located in the cytosolic fraction. The membrane fraction of the medulla contained significant amounts of Hg and Al: 120.7 and 32.0 mg/g protein, respectively. Cu and Zn were the most abundant trace elements found in the brush border membrane from the cortex: 120.7 and 68.2 mg/g protein, respectively. These quantities are largely in excess of what is bound, for example, to alkaline phosphatase. This suggests additional roles for trace elements in this membrane. The endogenous location of trace elements in the kidney could reflect a biochemical regulation related to metallic cofactors.Key words: brush border membrane, kidney, inorganic tissue content, element determination, inductively coupled plasma mass spectrometry.