title: Nitric oxide and depolarization induce hydroxyl radical generation.
abstract: Nitric oxide (NO) contributes to the extracellular potassium-ion concentration ([K+]o)-induced hydroxyl radical (*OH) generation. Cytotoxic free radicals such as peroxinitrite (ONOO-) and *OH may also be implicated in NO-mediated cell injury. NO is synthesized from L-arginine by NO synthase (NOS). NOS activation was induced by K+ depolarization. Oxidative modification of low-density lipoprotein (LDL) is thought to contribute to the production of oxygen derived-free radicals. However, LDL oxidation may be related to noradrenaline-induced *OH generation, but LDL oxidation may be unrelated to *OH generation via NOS activation. Abnormal levels of extracellular free dopamine (DA) and/or intraneuronal Ca2+ triggered by 1-methyl-4-phenylpyridinium ion (MPP+) may be detrimental to the functioning of dopaminergic nerve terminals in the striatum. Although [K+]o-induced depolarization enhances the formation of *OH product due to MPP+, the *OH generation via NOS activation may be unrelated to the DA-induced *OH generation. Depolarization enhances the formation of *OH products via NOS activation.
authors.affiliation: Department of Pharmacology, Oita Medical University, Japan. tobata@oita-med.ac.jp
authors.forename: Toshio
authors.initials: T
authors.lastname: Obata
mesh_terms: D000818:Animals; D017665:Hydroxyl Radical / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000378:metabolism; D008564:Membrane Potentials; D017072:Neostriatum / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D011188:Potassium / Q000378:metabolism
chemical_list: D008077:Lipoproteins, LDL; D009569:Nitric Oxide; D017665:Hydroxyl Radical; D019001:Nitric Oxide Synthase; D011188:Potassium