title: Superoxide anion formation from lucigenin: an electron spin resonance spin-trapping study.
abstract: Lucigenin (LC2+) is frequently used as a superoxide probe. To detect superoxide, lucigenin must be reduced to the lucigenin cation radical (LC.+). We show, using the phosphorylated spin trap 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide (DEPMPO), that lucigenin stimulates NADPH-dependent superoxide production by endothelial nitric oxide synthase (eNOS). The formation of the DEPMPO-superoxide adduct is calcium/calmodulin independent. DEPMPO-superoxide adduct formation is inhibited by diphenyleneiodonium and is abolished by superoxide dismutase. It is likely that eNOS/NADPH can reduce lucigenin to LC.+ which reduces oxygen to superoxide. Consequently, lucigenin cannot be used to measure superoxide formation.
authors.affiliation: Biophysics Research Institute, Medical College of Wisconsin, Milwaukee 53226-0509, USA.
authors.forename: J
authors.initials: J
authors.lastname: Vásquez-Vivar
authors.forename: N
authors.initials: N
authors.lastname: Hogg
authors.forename: K A
authors.initials: KA
authors.lastname: Pritchard
authors.forename: P
authors.initials: P
authors.lastname: Martasek
authors.forename: B
authors.initials: B
authors.lastname: Kalyanaraman
mesh_terms: D000166:Acridines / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D004578:Electron Spin Resonance Spectroscopy; D015335:Molecular Probes; D009249:NADP / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000302:isolation & purification / Q000378:metabolism; D010084:Oxidation-Reduction; D013481:Superoxides / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000166:Acridines; D015335:Molecular Probes; D013481:Superoxides; C033472:10,10'-dimethyl-9,9'-biacridinium; D009249:NADP; D019001:Nitric Oxide Synthase