Effects of allopurinol on iron storage in the rat.

Iron is stored in the liver and reticulo-endothelial system in the oxidized or ferric state and is bound to protein as ferritin or haemosiderin. Ferrous iron is less tightly bound to protein than is the ferric form. The mechanism of release of iron from ferritin is uncertain but there is some evidence that the xanthine oxidase system is of physiological importance in this step (Fig. 1). According to this hypothesis the reduction of ferric to ferrous ferritin occurs in association with the oxidation of xanthine and hypoxanthine to uric acid, xanthine oxidase acting as an electron donor in the reduction reaction and an electron acceptor in theoxidation reaction (Fridovich and Handler, 1958a, b).