Increased myocardial NADPH oxidase activity in human heart failure.
OBJECTIVE
This study was designed to investigate whether nicotinamide adenine dinucleotide 3-phosphate (reduced form) (NADPH) oxidase is expressed in the human heart and whether it contributes to reactive oxygen species (ROS) production in heart failure.


BACKGROUND
A phagocyte-type NADPH oxidase complex is a major source of ROS in the vasculature and is implicated in the pathophysiology of hypertension and atherosclerosis. An increase in myocardial oxidative stress due to excessive production of ROS may be involved in the pathophysiology of congestive heart failure. Recent studies have suggested an important role for myocardial NADPH oxidase in experimental models of cardiac disease. However, it is unknown whether NADPH oxidase is expressed in the human myocardium or if it has any role in human heart failure.


METHODS
Myocardium of explanted nonfailing (n = 9) and end-stage failing (n = 13) hearts was studied for the expression of NADPH oxidase subunits and oxidase activity.


RESULTS
The NADPH oxidase subunits p22(phox), gp91(phox), p67(phox), and p47(phox) were all expressed at messenger ribonucleic acid and protein level in cardiomyocytes of both nonfailing and failing hearts. NADPH oxidase activity was significantly increased in end-stage failing versus nonfailing myocardium (5.86 +/- 0.41 vs. 3.72 +/- 0.39 arbitrary units; p < 0.01). The overall level of oxidase subunit expression was unaltered in failing compared with nonfailing hearts. However, there was increased translocation of the regulatory subunit, p47(phox), to myocyte membranes in failing myocardium.


CONCLUSIONS
This is the first report of the presence of NADPH oxidase in human myocardium. The increase in NADPH oxidase activity in the failing heart may be important in the pathophysiology of cardiac dysfunction by contributing to increased oxidative stress.
Heymes
Christophe
C
Department of Cardiology, Guy's King's and St. Thomas's School of Medicine, King's College, London, United Kingdom.
Bendall
Jennifer K
JK
Ratajczak
Philippe
P
Cave
Alison C
AC
Samuel
Jane-Lise
JL
Hasenfuss
Gerd
G
Shah
Ajay M
AM
D000328:Adult; D015870:Gene Expression / Q000235:genetics / Q000502:physiology; D006333:Heart Failure / Q000201:enzymology* / Q000235:genetics* / Q000473:pathology; D006801:Humans; D066298:In Vitro Techniques; D008163:Luminescent Measurements; D008875:Middle Aged; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology*; D009249:NADP / Q000032:analysis* / Q000235:genetics* / Q000502:physiology; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology; D017382:Reactive Oxygen Species / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017382:Reactive Oxygen Species; D009249:NADP