Erythrocyte free radical and energy metabolism

The erythrocyte is a highly specialized cell whose main functions are oxyge n transport and the mediation of carbon dioxide transport. Energy productio n in the mature erythrocyte depends on glycolysis, with glucose as the prin cipal substrate. Glycolysis and the oxidative pentose phosphate pathway gen erate NADH and NADPH to reduce methemoglobin, which is being continuously p roduced, and the antioxidant glutathione, which is present in high concentr ations. Red blood cells are equipped with a highly effective antioxidant de fense even without the glutathione system. Compared with other cell types, they possess high activities of the most important antioxidant enzymes. Mos t of the nonenzymatic antioxidant capacity of whole blood is likewise local ized in the erythrocytes. Circulating red cells are mobile free radical sca vengers and provide antioxidant protection to other tissues and organs. An imbalance between pro-oxidant reactions and antioxidant defense is describe d in patients with chronic renal failure. Oxidative stress increases as ant ioxidant defenses are weakened by pro-oxidant hemodialysis factors; it incr eases further still in renal anemia with a very low red cell count. Thus in terms of free radical metabolism, the only arguments remaining over the co mplete correction of renal anemia are those in favor, with none against.