Cardiovascular Research Advance Access originally published online on September 19, 2007
Cardiovascular Research 2008 77(1):107-117; doi:10.1093/cvr/cvm022
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Pro-oxidant effect of transforming growth factor-β1 mediates contractile dysfunction in rat ventricular myocytes
1 Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, 985850 Nebraska Medical Center, Omaha, NE 68198-5850, USA
2 Department of Cardiology, The First Affiliated Hospital, Soochow University, Suzhou, Jiangsu 215006, PR China
3 Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA
4 Center for Redox Biology, University of Nebraska—Lincoln, Lincoln, NE, USA
* Corresponding author. Tel: +1 402 559 6056; fax: +1 402 559 4438. E-mail address: grozansk{at}unmc.edu
Aims: Transforming growth factor-β1 (TGF-β1) is a multifunctional cytokine that contributes to pathogenic cardiac remodelling via mechanisms that involve oxidative stress. However, the direct impact of TGF-β1 on contractile function of ventricular myocytes is incompletely understood.
Methods and results: Reactive oxygen species (ROS) production and intracellular glutathione (GSH) were measured by fluorescence microscopy in isolated rat ventricular myocytes pretreated with TGF-β1 (0.1–10 ng/mL). In separate studies, video edge detection measurements were made to evaluate myocyte contractile function, and confocal microscopy was used to monitor evoked Ca2+ transients. TGF-β1 (1 ng/mL) for 3–4 h significantly increased ROS production by 90% (P < 0.05) and decreased GSH by 34% (P < 0.05) compared with control. These changes paralleled a significant decrease in the rate of myocyte shortening and relaxation by 33% and 43%, respectively (0.5 Hz; P < 0.05), whereas fractional shortening was not altered. Ca2+ transients in TGF-β1-treated myocytes were characterized by a delayed peak and slowing in the rate of decay but no change in peak Ca2+ amplitude. Increased ROS production and GSH depletion by TGF-β1 were prevented by an NAD(P)H oxidase inhibitor or a free radical scavenger, both of which significantly mitigated TGF-β1-induced myocyte contractile dysfunction. Moreover, pretreating myocytes with exogenous GSH or the GSH precursor N-acetylcysteine also prevented myocyte contractile impairment and abnormal Ca2+ transients elicited by TGF-β1.
Conclusion: Our data suggest that TGF-β1-induced cardiomyocyte contractile dysfunction is associated with enhanced ROS production and oxidative alterations in Ca2+ handling proteins regulated by endogenous GSH.
KEYWORDS TGF; Redox; Glutathione; NAD(P)H oxidase; Oxidative stress
Time for primary review: 27 days