Renal bioavailability of selenium after supplementation with different forms of selenium: Ion probe and mass spectrometry study

Abstract

The bioavailability and safety of three different forms of selenium was evaluated in nephrocytes by secondary ion mass spectrometry. The distribution of the element in kidney cortex and the variations of selenium concentrations were established in mice supplemented with sodium selenite, selenomethionine, or Selenion®. Images of physiological selenium revealed the element in proximal tubules and found it to be particularly concentrated on the basal lamina of nephrocytes but undetectable in distal tubules. After treatments, the selenium images and the concentrations depended on the chemical form administered. The highest renal selenium concentrations were observed for selenomethionine and Selenion®. Early toxic effects of selenium supplementation were revealed only for high-dose sodium selenite as accumulations in some lysosomes. The widespread distribution of selenomethionine and Selenion® in proximal and distal tubular cells suggested that both were metabolized as methionine. Our results show the importance of physiological selenium in proximal tubule metabolism and bring to evidence that the bioavailability and safety of selenium depend on the chemical form administered. J. Trace Elem. Exp. Med. 13:367–380, 2000. © 2000 Wiley-Liss, Inc.