Glutathione and γ-glutamylcysteine in whole blood,plasma and erythrocytes

A method for the simultaneous determination of glutathione and γ-glutamyl-cysteine in capillary blood samples is described.The whole blood levels of glutathione and γ-glutamylcysteine are 1.09 ± 0.20 mmol/l and 25 ± 8 μmol/l (M ± S.D.), respectively. The plasma concentration is approximately 4 μmol/l for both compounds. It is important to treat the blood samples with a reducing agent before protein precipitation to release glutathione and γ-glutamylcysteine from disulfide linkages since, otherwise, 30–40% of the glutathione and 80% of the γ-glutamylcysteine is lost with the protein precipitate. Whole blood is preferable to washed erythrocytes for the analysis since the washing procedure involves losses of, especially, γ-glutamyl-cysteine.