Conversion of γ-glutamylcysteinylethyl ester to glutathione in rat hepatocytes

• Published in: Biochimica et biophysica acta 1996-08, Vol.1313 (1), p.47-53
• Main Authors: Nishida, Keiji, Ohta, Yoshiji, Ito, Madoka, Nagamura, Yoichi, Kitahara, Shigehisa, Fujii, Katsuhiko, Ishiguro, Isao
• Format: Article
• Language: English
• Subjects: Animals; Biological Transport; Dipeptides - metabolism; Esterase; Glutathione (reduced form); Glutathione - metabolism; Glutathione synthetase; Hepatocytes (rat); Kinetics; L-Lactate Dehydrogenase - metabolism; Liver - metabolism; Male; Maleates - pharmacology; Rats; Rats, Wistar; Sulfhydryl Compounds - metabolism; γ-Glutamylcysteinylethyl ester
• ISSN: 0167-4889; 0006-3002; 1879-2596
• DOI: 10.1016/0167-4889(96)00054-7

The conversion of γ-glutamylcysteinylethyl ester (γ-GCE) to glutathione in a reduced form (GSH) was examined using isolated rat hepatocytes pretreated with diethylmaleate, a GSH-depletor. Incubation of hepatocytes with 0.1 and 5.0 mM γ-GCE (γ-GCE-hepatocytes) over a 30-min period resulted in time-dependent increases in intracellular GSH and nonprotein-SH (NP-SH) concentrations. Hepatocytes incubated with 5.0 mM but not 0.1 mM GSH over a period of 30 min showed a time-dependent increase in intracellular GSH concentration. In the γ-GCE-hepatocytes pretreated with bis-( p-nitrophenyl)phosphate (BNPP), a non-specific esterase inhibitor, an enhancement of intracellular GSH concentration was markedly reduced. γ-GCE concentration in the γ-GCE-hepatocytes with BNPP pretreatment was significantly higher than that in the cells without BNPP pretreatment, although there was no difference in the total amount of intracellular NP-SH, i.e., γ-GCE, GSH, γ-glutamylcysteine, cysteine ethyl ester, and cysteine between both γ-GCE-hepato-cytes. The present results indicate that γ-GCE is transported into liver cells more easily than GSH itself, resulting in its conversion to GSH via esterase and glutathione synthetase within the cells.