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Stimulation of the NADPH oxidase in activated rat microglia removes nitric oxide but induces peroxynitrite production
Author(s) -
BalPrice Anna,
Matthias Anita,
Brown Guy C.
Publication year - 2002
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.0022-3042.2001.00675.x
Subject(s) - peroxynitrite , superoxide , nitric oxide , microglia , chemistry , superoxide dismutase , extracellular , nadph oxidase , biochemistry , neuroglia , lipopolysaccharide , nitric oxide synthase , microbiology and biotechnology , reactive oxygen species , biology , endocrinology , oxidative stress , inflammation , immunology , enzyme , organic chemistry , central nervous system
Cultured rat microglia produced extracellular superoxide at a rate of 814 ± 52 pmol/min/million cells when stimulated with phorbol 12‐myristate 13‐acetate (PMA) as measured by extracellular cytochrome c reduction. This superoxide production resulted in a rapid rate of superoxide dismutase‐sensitive nitric oxide (NO) breakdown (155 ± 30 pmol of NO/min/million cells) when NO was added to PMA stimulated microglia. Lipopolysaccharide/interferon‐γ (LPS/IFN‐γ)‐activated microglia produce NO at the rate of 145 ± 42 pmol/min/million cells and activated astrocytes at the rate of 51 ± 9 pmol/min/million cells as estimated by NO electrode. Both types of cells maintained a steady‐state level of 0.5–0.7 µ m NO, only in the presence of l ‐arginine. Addition of PMA to activated microglia (but not activated astrocytes) caused the rapid and complete disappearance of all extracellular NO (but was restored in the presence of superoxide dismutase) followed by the production of peroxynitrite (as measured by urate‐sensitive oxidation of dihydrorhodamine). Co‐incubation of activated microglia with cerebellar granule neurones resulted in NO inhibition of neuronal respiration, but this was rapidly removed by PMA‐induced breakdown of the NO. Thus, microglial NADPH oxidase can regulate the bioavailability of NO and the production of peroxynitrite.