Is there an inter-organ glutathione redox cycle?

Intracellular glutathione redox status is a function of the flux through glutathione peroxidase-glutathione reductase system. Specific activities of these two enzymes in rat liver cytosol and erythrocyte hemolysates were determined. Relative to glutathione peroxidase levels, glutathione reductase activity was about 15-fold more abundant in the rat liver than in erythrocytes. This is suggestive of greater capacity of the liver to reduce oxidised glutathione (GSSG). Based on these results and from the pattern of glutathione efflux from different cells and tissues [Sies, H. & Akerboom, T.P.M. (1984) Methods Enzymol. 105, 445-451], it is speculated that an interorgan glutathione redox cycle may be operative wherein liver is central to the reduction of GSSG and other disulphides.