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GSH oxidation to GSSG preceded seleno‐L‐methionine cytotoxicity in freshly isolated rat hepatocytes
Author(s) -
Elfarra Adnan A,
Krause Renee J,
Goth Stephen W
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a813-d
Subject(s) - glutathione , hepatocyte , trypan blue , cytotoxicity , chemistry , extracellular , intracellular , biochemistry , oxidative stress , methionine , glutathione disulfide , metabolism , viability assay , enzyme , in vitro , amino acid
SeMet has anti‐cancer, chemopreventive and toxic properties. Recently, we have shown that purified rat liver FMO3 and FMO1 can oxidize SeMet (Km = 0.11 and 7.8 mM, respectively) to yield L‐methionine selenoxide (MetSeO). In the presence of GSH, MetSeO can be recycled back to SeMet and cause GSSG formation. Thus, in the present study, we examined the cytotoxicity of SeMet in freshly isolated hepatocytes from male Sprague‐Dawley rats after incubations for 0–90 min with SeMet (0.05–0.5 mM) at physiological conditions (pH 7.4, 37°C). Cytotoxicity was assessed by the trypan blue exclusion method. Intracellular and extracellular GSH and GSSG levels were also measured using an enzymatic recycyling method. The results show SeMet exhibited dose‐ and time‐dependent loss of hepatocyte viability. Interestingly, at 0.5 mM SeMet, significant decreases in cellular GSH levels and significant increases in extracellular GSSG levels were consistently observed at time points (30 and 60 min) that preceded the loss of hepatocyte viability. Thus, oxidative metabolism of SeMet to MetSeO and the oxidative stress resulting from the conversion of GSH to GSSG may play a significant role in the toxic properties of SeMet in hepatocytes. (Supported by NIH Grant DK44295).