Identification of urinary tellurium metabolite in rats administered sodium tellurite
Tellurium (Te) is one of the important metalloids used in industry, and is ubiquitously found in the environment. However, the biological and toxicological effects of Te are still unclear despite its being recognized as a hazardous element. In this study, we attempted to identify urinary Te metabolites (UTMs) in rats by HPLC-ICP-MS and electrospray ionization (ESI)-MS. To unambiguously identify UTMs, two different chromatographic mechanisms, i.e., multi-mode gel filtration and cation exchange columns, were employed. The major UTM detected after ingestion of tellurite was trimethyltelluronium, and no urinary sugar metabolites containing Te were detected despite the fact that the major urinary selenometabolite was a selenosugar (methyl-2-acetamido-2-deoxy-1-seleno-β-D-galactopyranoside). Interestingly, the ingestion of tellurite enhanced the excretion of selenometabolites in urine. These results suggest that Te is discretely metabolized from selenium (Se), an essential element belonging to the same group, although it affects the metabolism of Se in rats. Thus, the disturbance of Se metabolism, i.e., the induction of Se deficiency, may be one of the potential toxic effects of Te.