title: Inhibition of mitochondrial superoxide generation in rat alveolar macrophages by 12-O-tetradecanoylphorbol-13-acetate: potential role of protein kinase C.
abstract: We have observed that lucigenin-derived chemiluminescence (CL) measures superoxide anion (O2-) production from two major cellular compartments in rat alveolar macrophages (AMs): extracellular O2- produced by NADPH oxidase; and intracellular O2- produced by the reduction of molecular oxygen by the mitochondrial electron transport chain. Although the treatment of AMs with 30 ng/mL 12-O-tetradecanoyl phorbol-13-acetate (TPA) increases the production of O2- by NADPH oxidase, the net result of TPA addition monitors is a decrease in lucigenin-derived CL resulting from inhibition of mitochondrial-derived O2- production. Since protein kinase C (PKC) has been shown to be the cellular receptor through which TPA mediates its effects, it was postulated that activation of PKC inhibits mitochondrial-derived O2- production as measured by lucigenin-derived CL. Studies performed with 50 microM H-7 (a PKC inhibitor) support this hypothesis by blocking the inhibition of mitochondrial-derived CL by TPA, while HA-1004, a negative control for H-7, had no effect on the system. These results suggest that mitochondrial respiration may be modulated by the actions of PKC. Moreover, this observation suggests a novel mechanism whereby chemicals which activate PKC may affect cellular function through modulation of mitochondrial activity.
authors.affiliation: Department of Environmental Health Sciences, Johns Hopkins School of Hygiene and Public Health, Baltimore, MD 21205.
authors.forename: S J
authors.initials: SJ
authors.lastname: Rembish
authors.forename: Y
authors.initials: Y
authors.lastname: Yang
authors.forename: M A
authors.initials: MA
authors.lastname: Trush
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000166:Acridines / Q000378:metabolism; D000818:Animals; D003574:Cytochrome c Group / Q000378:metabolism; D007546:Isoquinolines / Q000494:pharmacology; D007700:Kinetics; D008163:Luminescent Measurements; D016676:Macrophages, Alveolar / Q000648:ultrastructure*; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D000166:Acridines; D003574:Cytochrome c Group; D007546:Isoquinolines; D010879:Piperazines; D013481:Superoxides; C033472:10,10'-dimethyl-9,9'-biacridinium; D009249:NADP; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D013482:Superoxide Dismutase; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate