The peroxynitrite evoked contractile depression can be partially reversed by antioxidants in human cardiomyocytes.
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 (F(o)) and the maximal turnover rate of the cross-bridge cycle (k(tr,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 F(o) in a concentration-dependent manner (EC(50,peroxynitrite) = 49 microM; EC(50,DTDP) = 2.75 mM). However, k(tr,max) was decreased only by 2.5-mM DTDP, but not by 50 microM peroxynitrite. The diminution of F(o) 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 F(o) and free SH groups evoked by 2.5-mM DTDP were completely reverted by DTT. In contrast, DTT induced only a partial restoration in F(o) (DeltaF(o,): approximately 13%; P < 0.05) despite full reversion in protein SH content after 50 microM peroxynitrite. Although, NAC or DTT were equally effective on F(o) after peroxynitrite exposures, NAC or GSH did not restore F(o) or k(tr,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.
Hertelendi
Zita
Z
Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
Tóth
Attila
A
Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
Borbély
Attila
A
Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
Galajda
Zoltán
Z
Center of Cardiac Surgery, Institute of Cardiology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
Édes
István
I
Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
Tósaki
Árpád
Á
Department of Pharmacology, Faculty of Pharmacy, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
Papp
Zoltán
Z
Division of Clinical Physiology, Institute of Cardiology, Faculty of Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.
D000328:Adult; D000975:Antioxidants / Q000494:pharmacology*; D005260:Female; D006321:Heart / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000494:pharmacology*
D000975:Antioxidants; D030421:Peroxynitrous Acid