title: Effect of medium pH on glutathione redox cycle in cultured human umbilical vein endothelial cells.
abstract: Impairments of the glutathione redox cycle in cultured endothelial cells under acidic pH conditions were measured. Glutathione-dependent H2O2-degrading activities decreased by 20% (P < .01) at pH 6 and by 51% (P < .01) at pH 4 compared with activities at pH 7.4 1 hour after a change with fresh medium. Intracellular reduced glutathione (GSH) content increased by 85% (P < .01) following the change with pH 7.4 medium. Such increases in GSH content were impaired after exposure to acidic medium. After exposure to 500 mumol/LH2O2, intracellular GSH content decreased by 61% compared with the level obtained in the absence of H2O2 at pH 7.4 (P < .01). Compared with the level at pH 7.4, the H2O2-induced decrease in intracellular GSH content was 32% lower (P < .01) at pH 6 and did not change at all at pH 4. After exposure to 500 mumol/L H2O2, the intracellular oxidized glutathione (GSSG) content increased by 160% at pH 7.4 (P < .01), 370% at pH 6 (P < .01), and 90% at pH 4 compared with treatment without H2O2, respectively. After exposure to 500 mumol/L H2O2, the release of GSSG from cells at pH 6 decreased by 38% compared with the value found at pH 7.4 (P < .05), and the release at pH 4 completely disappeared. Both glutathione peroxidase (GPO) and glutathione reductase activities decreased as a function of a decrease in pH from 7.4 to 4.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Third Department of Medicine, Shiga University of Medical Science, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Ikebuchi
authors.forename: A
authors.initials: A
authors.lastname: Kashiwagi
authors.forename: T
authors.initials: T
authors.lastname: Asahina
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Y
authors.initials: Y
authors.lastname: Takagi
authors.forename: Y
authors.initials: Y
authors.lastname: Nishio
authors.forename: H
authors.initials: H
authors.lastname: Hidaka
authors.forename: R
authors.initials: R
authors.lastname: Kikkawa
authors.forename: Y
authors.initials: Y
authors.lastname: Shigeta
mesh_terms: D000143:Acids / Q000494:pharmacology*; D002478:Cells, Cultured; D003470:Culture Media / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005978:Glutathione / Q000031:analogs & derivatives / Q000378:metabolism*; D019803:Glutathione Disulfide; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D014471:Umbilical Veins / Q000378:metabolism*
chemical_list: D000143:Acids; D003470:Culture Media; D006861:Hydrogen Peroxide; D005978:Glutathione; D019803:Glutathione Disulfide