Enzymatic superoxide-dismutase activity is believed to be important in defense against the toxic effects of superoxide. Although superoxide dismutases are among the best studied proteins, numerous questions remain concerning the specific biological roles of the various superoxide-dismutase types. In part, this is because the proposed damaging effects of superoxide are manifold, ranging from ina...

Optic neuropathy is the leading cause of irreversible blindness, and a paradigm for central nervous system axonal disease. The primary event is damage to retinal ganglion cell axons, with subsequent death of the cell body by apoptosis. Trials of neuroprotection for these and other neuronal diseases have mostly failed, primarily because mechanisms of neuroprotection in animals do not necessarily...

Myeloperoxidase uses hydrogen peroxide to oxidize numerous substrates to hypohalous acids or reactive free radicals. Here we show that neutrophils oxidize melatonin to N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) in a reaction that is catalyzed by myeloperoxidase. Production of AFMK was highly dependent on superoxide but not hydrogen peroxide. It did not require hypochlorous acid, singlet...

Paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride) is widely used as a redox cycler to stimulate superoxide production in organisms, cells, and mitochondria. This superoxide production causes extensive mitochondrial oxidative damage, however, there is considerable uncertainty over the mitochondrial sites of paraquat reduction and superoxide formation. Here we show that in yeast and mammalian...

Much attention has been focused on the role of nitric oxide in hypertension and cardiovascular disease. More recently, the role of superoxide anion and its interaction with nitric oxide has been investigated in this context. This review will concentrate on the role of superoxide in human and experimental hypertension, paying particular attention to the potential sources of superoxide within the...

BACKGROUND AND PURPOSE Seizures cause cerebrovascular responses similar to those seen in conditions such as acute hypertension, ischemia/reperfusion, or fluid-percussion brain injury, which are associated with the generation of superoxide. Accordingly, we studied production of superoxide in experimental seizures. METHODS Superoxide production was measured in anesthetized cats equipped with do...

Mitochondria are a major source of superoxide, formed by the one-electron reduction of oxygen during electron transport. Superoxide initiates oxidative damage to phospholipids, proteins and nucleic acids. This damage may be a major cause of degenerative disease and aging. In isolated mitochondria, superoxide production on the matrix side of the membrane is particularly high during reversed elec...

Lucifer yellow CH (LY), a fluorescent membrane-impermeable cell marker dye, has been routinely loaded into cells through recording electrodes to visualize these cells after electrophysiological investigation, without considering its pharmacological effect. Recently, we showed that the exposure of cells loaded with LY to light for microscopy produced unidentified radical species that retarded th...

The interplay between nitric oxide and superoxide to form peroxynitrite is a major biological process that competes in a remarkably subtle fashion with superoxide dismutase in vivo. The complex interactions between superoxide, nitric oxide reveals some extraordinary features about the difficulties of effectively scavenging of superoxide in a biological system. The discovery of dominant mutation...