Oxygen free radical release in human failing myocardium is associated with increased activity of rac1-GTPase and represents a target for statin treatment.
BACKGROUND
Reactive oxygen species (ROS) contribute to the development of heart failure. A potential source of myocardial ROS is the NADPH oxidase, which is regulated by the small GTP-binding protein rac1. Isoprenylation of rac1 can be inhibited by statin therapy. Thus, we examined ROS and rac1 in human failing myocardium and tested their regulation by statins in vivo.


RESULTS
In human left ventricular myocardium from patients with ischemic cardiomyopathy (ICM) or dilated cardiomyopathy (DCM), NADPH oxidase activity was increased 1.5-fold compared with nonfailing controls (P<0.05, n=8). In failing myocardium, increased oxidative stress determined by measurements of lipid peroxidation and aconitase activity was associated with increased translocation of rac1 from the cytosol to the membrane. Pull-down assays revealed a 3-fold increase of rac1-GTPase activity in ICM and DCM. In parallel, membrane expression of the NADPH oxidase subunit p47phox, but not p67phox, was upregulated in failing compared with nonfailing myocardium. In right atrial myocardium from patients undergoing cardiac surgery who were prospectively treated with atorvastatin or pravastatin (40 mg/d, 4 weeks), rac1-GTPase activity was decreased to 67.9+/-12% and 65.6+/-13.8% compared with patients without statin (P<0.05, n=8). Both atorvastatin and pravastatin significantly reduced angiotensin II-stimulated but not basal NADPH oxidase activity.


CONCLUSIONS
Failing myocardium of patients with DCM and ICM is characterized by upregulation of NADPH oxidase-mediated ROS release associated with increased rac1 activity. Oral statin treatment inhibits myocardial rac1-GTPase activity. These data suggest that extrahepatic effects of statins can be observed in humans and may be beneficial for patients with chronic heart failure.
Maack
Christoph
C
Klinik und Poliklinik für Innere Medizin III, Universität des Saarlandes, Homburg/Saar, Germany.
Kartes
Tanja
T
Kilter
Heiko
H
Schäfers
Hans-Joachim
HJ
Nickenig
Georg
G
Böhm
Michael
M
Laufs
Ulrich
U
D002303:Cardiac Output, Low / Q000188:drug therapy / Q000201:enzymology* / Q000378:metabolism; D002311:Cardiomyopathy, Dilated / Q000150:complications; D002462:Cell Membrane / Q000201:enzymology; D016503:Drug Delivery Systems; D005260:Female; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications; D009206:Myocardium / Q000201:enzymology* / Q000378:metabolism; D019255:NADPH Oxidases / Q000378:metabolism; D018384:Oxidative Stress; D010750:Phosphoproteins / Q000378:metabolism; D021381:Protein Transport; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015854:Up-Regulation; D020830:rac1 GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*
D005609:Free Radicals; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D010750:Phosphoproteins; D017382:Reactive Oxygen Species; C079789:neutrophil cytosol factor 67K; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D020830:rac1 GTP-Binding Protein