The peroxynitrite evoked contractile depression can be partially reversed by antioxidants in human cardiomyocytes

Zita Hertelendi, Attila Tóth, Attila Borbély, Zoltán Galajda, István Édes, Árpád Tósaki, Zoltán Papp

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3 Citations (Scopus)

Abstract

In this study, we aimed to determine the contribution of peroxynitrite-dependent sulfhydryl group (SH) oxidation to the contractile dysfunction in permeabilized left ventricular human cardiomyocytes using a comparative approach with the SH-oxidant 2,2′-dithiodipyridine (DTDP). Additionally, different antioxidants: dithiothreitol (DTT), reduced glutathione (GSH) or N-acetyl-L-cysteine (NAC) were employed to test reversibility. Maximal isometric active force production (Fo) and the maximal turnover rate of the cross-bridge cycle (ktr,max) illustrated cardiomyocyte mechanics. SH oxidation was monitored by a semi-quantitative Ellman's assay and by SH-specific protein biotinylation. Both peroxynitrite and DTDP diminished Fo in a concentration-dependent manner (EC50,peroxynitrite = 49 μM; EC50,DTDP = 2.75 mM). However, ktr,max was decreased only by 2.5-mM DTDP, but not by 50 μM peroxynitrite. The diminution of Fo to zero by DTDP was paralleled by the complete elimination of the free SH groups, while the peroxynitrite-induced maximal reduction in free SH groups was only to 58 ± 6% of the control (100%). The diminutions in Fo and free SH groups evoked by 2.5-mM DTDP were completely reverted by DTT. In contrast, DTT induced only a partial restoration in Fo (ΔFo,:∼13%; P < 0.05) despite full reversion in protein SH content after 50 μM peroxynitrite. Although, NAC or DTT were equally effective on Fo after peroxynitrite exposures, NAC or GSH did not restore Fo or ktr,max after DTDP treatments. Our results revealed that the peroxynitrite-evoked cardiomyocyte dysfunction has a small, but significant component resulting from reversible SH oxidation, and thereby illustrated the potential benefit of antioxidants during cardiac pathologies with excess peroxynitrite production.

Original languageEnglish
Pages (from-to)2200-2209
Number of pages10
JournalJournal of Cellular and Molecular Medicine
Volume13
Issue number8 B
DOIs
Publication statusPublished - Aug 1 2009

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Keywords

  • Cardiomyocyte
  • Heart
  • Ischaemic reperfusion injury
  • Nitrosative/oxidative stress
  • Peroxynitrite
  • Sulfhydryl groups

ASJC Scopus subject areas

  • Molecular Medicine
  • Cell Biology

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