title: Antioxidant adaptive response in human blood mononuclear cells exposed to UVB.
abstract: Human blood mononuclear cells exposed to UVB radiation develop increased antioxidant enzyme activities. Catalase (5.50 +/- 0.65 pmol (mg protein)-1), CuZn-superoxide dismutase (16.7 +/- 2.1 pmol (mg protein)-1), Mn-superoxide dismutase (11.3 +/- 1.7 pmol (mg protein)-1), Se-dependent glutathione peroxidase (13.2 +/- 1.5 mU (mg protein)-1) and Se-independent glutathione peroxidase (3.30 +/- 0.52 mU (mg protein)-1) activities increase by 1.3-1.5-fold from the control activities after exposure to 0.3 W m-2 of 280-315 nm light for 15 min and a 3 h dark incubation period. DT-diaphorase activity (2.86 +/- 0.21 mumol DCPIP min-1 (mg protein)-1) increases threefold from the indicated control values. In contrast, cytochrome oxidase (0.36 +/- 0.04 min-1 (k') (mg protein)-1) and succinate dehydrogenase (3.06 +/- 0.25 mumol DCPIP min-1 (mg protein)-1) activities remain unchanged during the same irradiation and incubation period. The treatment of cells with cycloheximide prevents the response triggered by UVB exposure. These findings suggest that an inducible antioxidant defence mechanism operates on photo-oxidative stress and that both superoxide dismutase and DT-diaphorase may display a concerted antioxidant role.
authors.affiliation: Institute of Biochemistry and Biophysics, School of Pharmacy and Biochemistry, University of Buenos Aires, Argentina.
authors.forename: S
authors.initials: S
authors.lastname: Alvarez
authors.forename: A
authors.initials: A
authors.lastname: Boveris
mesh_terms: D000222:Adaptation, Physiological; D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D003576:Electron Transport Complex IV / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D006801:Humans; D009000:Monocytes / Q000187:drug effects / Q000201:enzymology / Q000528:radiation effects*; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D013385:Succinate Dehydrogenase / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D000975:Antioxidants; D011500:Protein Synthesis Inhibitors; D003513:Cycloheximide; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D013385:Succinate Dehydrogenase; D016660:NAD(P)H Dehydrogenase (Quinone); D003576:Electron Transport Complex IV