Blood Glutathione Disulfide: In Vivo Factor or in Vitro Artifact?

tathione disulfide (GSSG) in human blood/erythrocytes varies widely (1 to>500 mol/L), as does that of reduced glutathione (GSH) to a lesser extent. We have identified and investigated possible pitfalls in measurement of both GSH and GSSG. Methods: We measured GSH and GSSG using a spec-trophotometer with a modification of the GSH recycling method; the same samples were also measured by re-versed-phase HPLC after derivatization of thiols (di-thiothreitol was used to reduce disulfides) with mono-bromobimane. The thiol-bimane adduct was measured by a fluorescence detector. Results: Measured GSH/GSSG concentrations were af-fected by the following: (a) oxidation of thiols in acid-ified samples; (b) oxidation after restoring neutral-alka