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. Author manuscript; available in PMC: 2010 Nov 15.
Published in final edited form as: Free Radic Biol Med. 2009 Aug 26;47(10):1329–1338. doi: 10.1016/j.freeradbiomed.2009.08.021

Fig 1. Redox poise in biologic systems.

Fig 1

Steady-state redox potentials (Eh) of individual thiol/disulfide couples are displaced from equilibrium both within aqueous compartments and between subcellular compartments. For instance, the redox potential (Eh) for glutathione is the half-cell, 2-electron reduction potential of the couple consisting of GSSG and 2H+/2GSH, expressed relative to a standard 2H+/H2 electrode. The present assay was developed to determine the steady-state GSH/GSSG redox potential in plasma. Results show that plasma Cys/CySS redox potential is oxidized relative to that of GSH/GSSG, and the Eh values for each of these couples is highly oxidized relative to cellular and tissue thiol/disulfide redox potentials. Note that the steady-state Eh values are dependent upon the pH of the compartment. The values given in this figure are appropriate for the pH of each respective compartment. Other extracellular fluids are also more oxidized than cell and tissue values, but these have not been studied extensively.