title: Protective effect of antioxidants against sarcoplasmic reticulum (SR) oxidation by Fenton reaction, however without prevention of Ca-pump activity.
abstract: The Ca(2+)-ATPase of the sarcoplasmic reticulum (SERCA) of rabbit skeletal muscle was oxidized by Fe2+/H2O2/ascorbic acid (AA), a system which generates HO(.) radicals according to the Fenton reaction: (Fe2(+)+H2O2-->HO(.)+OH(-)+Fe(3+)) under conditions similar to the pathological state of inflammation. Under these conditions, when hydroxyl-radicals and/or ferryl-radicals are generated, a 50% decrease of the SERCA activity was observed, a significant decrease of SH groups and an increase of protein carbonyl groups and lipid peroxidation were identified. Two new bands, time dependent in density, appeared in the SERCA protein electrophoresis after incubation with the Fenton system (at approximately 50 and 75kDa), probably due to structural changes as supported also by trypsin digestion. Immunoblotting of DNPH derivatized protein bound carbonyls detected a time dependent increase after incubation of SERCA with the Fenton system. Trolox and the pyridoindole stobadine (50microM) protected SR against oxidation induced via the Fenton system by preventing SH group oxidation and lipid peroxidation. Pycnogenol((R)) and EGb761 (40microg/ml) protected SERCA in addition against protein bound carbonyl formation. In spite of the antioxidant effects, trolox and stobadine were not able to prevent a decrease in the SERCA Ca(2+)-ATPase activity. Pycnogenol and EGb761 even enhanced the decrease of the Ca(2+)-ATPase activity induced by the Fenton system, probably by secondary oxidative reactions.
authors.affiliation: Research Institute for Environmental Medicine gGmbH at the Heinrich-Heine-University, Duesseldorf, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Voss
authors.forename: Martina
authors.initials: M
authors.lastname: Engels
authors.forename: Miriam
authors.initials: M
authors.lastname: Strosova
authors.forename: Tilman
authors.initials: T
authors.lastname: Grune
authors.forename: Lubica
authors.initials: L
authors.lastname: Horakova
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000378:metabolism; D002243:Carbolines / Q000494:pharmacology; D002839:Chromans / Q000494:pharmacology; D005296:Ferrous Compounds / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D020441:Ginkgo biloba; D006861:Hydrogen Peroxide / Q000378:metabolism; D007249:Inflammation / Q000188:drug therapy / Q000503:physiopathology; D015227:Lipid Peroxidation / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects*; D010936:Plant Extracts / Q000494:pharmacology; D050050:Protein Carbonylation / Q000187:drug effects; D011817:Rabbits; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000187:drug effects*; D013552:Swine; D013997:Time Factors; D000096983:Ginkgo Extract
chemical_list: D000975:Antioxidants; D001205:Ascorbic Acid; D002243:Carbolines; D002839:Chromans; D005296:Ferrous Compounds; D005419:Flavonoids; D006861:Hydrogen Peroxide; D010936:Plant Extracts; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C063170:Ginkgo biloba extract; D000096983:Ginkgo Extract; C024070:pycnogenols; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; C100106:dicarbine