Peroxynitrite-induced luminol chemiluminescence.
Vascular endothelial cells, smooth muscle cells, macrophages, neutrophils, Kupffer cells and other diverse cell types generate superoxide (O2.-) and nitric oxide (.NO), which can react to form the potent oxidant peroxynitrite anion (ONOO-). Peroxynitrite reacted with luminol to yield chemiluminescence which was greatly enhanced by bicarbonate. The quantum chemiluminescence yield of the ONOO- reaction with luminol in bicarbonate was approx. 10(-3). Chemiluminescence was superoxide dismutase-inhibitable, indicating that O2.- was a key intermediate for chemiexcitation. O2.- appears to be formed secondarily to the reaction of a bicarbonate-peroxynitrite complex with luminol, yielding luminol radical and O2.-. Luminol radical reacts with O2.- to form the unstable luminol endoperoxide, which follows the light-emitting pathway. Neither .NO nor O2.- alone were capable of directly inducing significant luminol chemiluminescence in our assay systems. These results suggest that ONOO- can be a critical unrecognized mediator of cell-derived luminol chemiluminescence reported in previous studies. In addition, it is shown that bicarbonate can participate in secondary oxidation reactions after reacting with ONOO-.
Radi
R
R
Department of Anesthesiology, University of Alabama, Birmingham 35233-6810.
Cosgrove
T P
TP
Beckman
J S
JS
Freeman
B A
BA
D000975:Antioxidants / Q000494:pharmacology; D001639:Bicarbonates / Q000378:metabolism / Q000494:pharmacology; D005609:Free Radicals; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008163:Luminescent Measurements; D008165:Luminol / Q000737:chemistry* / Q000378:metabolism; D009566:Nitrates / Q000494:pharmacology*; D010084:Oxidation-Reduction; D013053:Spectrophotometry; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism
D000975:Antioxidants; D001639:Bicarbonates; D005609:Free Radicals; D009566:Nitrates; D013481:Superoxides; C039642:peroxynitric acid; D008165:Luminol; D013482:Superoxide Dismutase