Oxidative damage to Ca^{2+}-ATPase sarcoplasmic reticulum by HOCl and protective effect of some antioxidants

Issue title: HNE and Further Lipid Peroxidation Products

Article type: Research Article

Authors: Štrosová, Miriam | Škuciová, Mária | Horáková, Lúbica

Affiliations: Institute of Experimental Pharmacology, Slovak Academy of Sciences, Bratislava, Slovak Republic

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Abstract: Injury of rabbit skeletal sarcoplasmic reticulum (SR) induced by hypochlorous acid (HOCl) was studied. HOCl inhibited Ca^{2+}-ATPase activity in a concentration-dependent manner (IC_{50}=100 μmol/l). The concentration of 13.5 μmol/l HOCl reduced the level of sulfhydryl (SH) groups by 50%, yet it did not influence the enzyme activity. In comparison with SH group oxidation and enzyme activity inhibition, a significantly longer time was necessary for the generation of protein carbonyls in SR injured by HOCl. Protective effects of some antioxidants (stobadine, trolox, EGb 761, Pycnogenol®) were studied in SR oxidatively injured by HOCl. Trolox and EGb 761 exerted a protective effect on ATPase activity and on SH groups of SR oxidatively modified by HOCl. Stobadine and Pycnogenol® inhibited markedly protein carbonyl formation. Stobadine was the only antioxidant able to scavenge HOCl. In conclusion, the protective effects of antioxidants against decrease of Ca^{2+}-ATPase activity induced by HOCl might be caused by protection of SH groups. The compounds with both antioxidant and Ca^{2+}-ATPase protecting effect offer dual defense against tissue damage occurring, e.g. in aging process.

Keywords: Ca[TeX:] ^{2+}-ATPase, HOCl, reactive oxygen species, antioxidants, stobadine, trolox, Egb 761, Pycnogenol®

Journal: BioFactors, vol. 24, no. 1-4, pp. 111-116, 2005