Red cells from glutathione peroxidase-1–deficient mice have nearly normal defenses against exogenous peroxides

The role of glutathione peroxidase in red cell anti-oxidant defense was examined using erythrocytes from mice with a genetically engineered disruption of the glutathione peroxidase-1 (GSHPx-1) gene. Because GSHPx-1 is the sole glutathione peroxidase in the erythrocyte, all red cell GSH peroxidase activity was eliminated. Oxidation of hemoglobin and membrane lipids, using the cis-parinaric acid assay, was determined during oxidant challenge from cumene hydroperoxide and H2O2. No difference was detected between wild-type red cells and GSHPx-1–deficient cells, even at high H2O2 exposures. Thus, GSHPx-1 appears to play little or no role in the defense of the erythrocyte against exposure to peroxide. Simultaneous exposure to an H2O2 flux and the catalase inhibitor 3-amino-1,2,4-triazole supported this conclusion. Hemoglobin oxidation occurred only when catalase was depleted. Circulating erythrocytes from the GSHPx-1–deficient mice exhibited a slight reduction in membrane thiols, indicating that high exposure to peroxides might occur naturally in the circulation.