SUPEROXIDE ANION FORMATION FROM LUCIGENIN - AN ELECTRON-SPIN-RESONANCE SPIN-TRAPPING STUDY

Lucigenin (LC(2+)) 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-diethoxyphosp horyl-5-methyl-1-pyrroline N-oxide (DEPMPO), that lucigenin stimulates NADPH-dependent superoxide production by endothelial nitric oxide syn thase (eNOS), The formation of the DEPMPO-superoxide adduct is calcium /calmodulin independent, DEPMPO-superoxide adduct formation is inhibit ed by diphenyleneiodonium and is abolished by superoxide dismutase, It is likely that eNOS/NADPH can reduce lucigenin to LC(.+) which reduce s oxygen to superoxide, Consequently, lucigenin cannot be used to meas ure superoxide formation. (C) 1997 Federation of European Biochemical Societies.