Reduction of ferrylmyoglobin in rat diaphragm

The oxidation of myoglobin was monitored by transmission spectroscopy in isolated, superfused preparations of rat diaphragms. In its deoxygenated form, during anoxia, myoglobin was oxidized by adding hydrogen peroxide (1.0 mM) to its ferryl form (FeIV). On the other hand, peroxide-induced formation of ferrylmyoglobin was not observed when the perfusate contained oxygen. Ferrylmyoglobin was visualized after its derivatization with Na2S to form sulfmyoglobin. Depending on the time of addition, ascorbate (4.0 mM) or ergothioneine (2.0 mM) either prevented the formation of or dissipated ferrylmyoglobin. These agents are known to be reductants of this hypervalent form of myoglobin. In addition to providing the first demonstration of ferrylmyoglobin in skeletal muscle, these observations are consistent with the concept that oxidation of myoglobin to hypervalent states might be an important event in the initiation of muscle damage associated with anoxia and reoxygenation. The rapid reduction of myoglobin would prevent peroxidatic alterations of essential cellular constituents by ferrylmyoglobin.