Identification of Distinct Pathways for Superoxide Generation in Mouse Macrophages: An Investigation Using a Chemiluminescence Probe Specific for Superoxide Anion

Abstract

Dependency of superoxide anion (O₂^-) generation on protein kinase C (PKC) or calmodulin (CaM) in macrophages (MPs) was investigated using a O₂^--specific chemiluminescence probe with the Cypridina luciferin analog 2-methyl-6-(p-niethoxyphenyl)-3, 7-dihydroimidazo[1, 2-a]-pyrazin-3-one (MCLA). In opsonized zymosan (OZ)-stimulated MPs, 40% of the MCLA-dependent chemiluminescence disappeared when the PKC inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7) or the CaM antagonist N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) was added. In MPs stimulated by 12-o-tetradecanoylphorbol-13-acetate (TPA), addition of H-7 strikingly lowered MCLA-dependent Chemiluminescence, but W-7 had only a little effect. These results indicate that both PKC and CaM are involved in OZ-stimulated O₂^- generation in MPs and that TPA-stimulated O₂^- generation depends not on CaM but on PKC.