Transport of selenium species in Caco-2 cells: Analytical approach employing the Ussing chamber technique and HPLC-ICP-MS

Essential trace elements such as selenium (Se) play a crucial role in health and diseases. Investigations of the transport and absorption of different Se species in vivo and in vitro consider only one Se species in a systematic manner. Thus, transport of four Se compounds (at concentrations of 100 and 400 mu g L-1) namely selenite (SeO32-), selenate (SeO42-), selenomethionine (SeMet), and Se-methylselenocysteine (MeSEC) was compared using the Caco-2 cell line and the Ussing chamber system. For analytical measurements, an HPLC-ICP-DRC-MS method was developed and characterized. For the investigated Se species, limits of quantification were 0.5 mu g L-1 while trueness was tested using the certified reference material SELM-1. Se species were added to the apical compartment of the Ussing chamber system either separately or simultaneously. Notably, no transport for SeO32- from apical to basolateral side was observed. Transport efficacy after 120 min was the highest (9.1%) for SeMet in single species experiments, whereas SeO42- transport was the highest (7.9%) associated with simultaneous adding of Se species. Furthermore, changes in rank order of the apparent permeability coefficients P-app were obtained in mixture experiments as compared to the single species approaches. Finally, experimental data demonstrate alterations in transport of SeMet, MeSEC, and SeO42- suggesting interactions between Se species and changes in the transport behavior. (C) 2013 Elsevier B.V. All rights reserved.