Upregulation of glucose-6-phosphate dehydrogenase and NAD(P)H oxidase activity increases oxidative stress in failing human heart.

Abstract

BACKGROUND:

We previously found that higher NADPH levels produced by glucose-6-phosphate dehydrogenase (G6PD) can enhance myocardial superoxide generation by NAD(P)H oxidase in a dog model of dilated cardiomyopathy. Therefore, we tested whether G6PD activity is elevated and enhances NADPH level and increases NAD(P)H oxidase-derived superoxide production in the myocardium from patients with heart failure from ischemic cardiomyopathy.

METHODS AND RESULTS:

Surgical discards of left ventricle were collected from 8 congestive heart failure patients undergoing surgical ventricular restoration procedures, whereas control left ventricle tissue was obtained from 5 normal donor hearts deemed not suitable for transplantation. Biochemical assays were performed in tissue homogenates. We found that superoxide and hydrogen peroxide were elevated, respectively, by 9- and 3-fold in failing versus normal hearts (P < .05). The NAD(P)H oxidase inhibitors gp91(ds-tat), apocynin, and diphenyleneiodonium, significantly inhibited superoxide generation by approximately 75%, 89%, and 91%, respectively. Superoxide production by NAD(P)H oxidase increased 10- and 3-fold by adding NADPH (100 micromol/L) and NADH (100 micromol/L), respectively, in a DPI- and gp91(ds-tat)-inhibitable manner. Interestingly, chelerythrine, a PKC inhibitor, and PP2, a Src kinase family inhibitor, reduced G6PD activity (0.29 +/- 0.04 nM x min x mg protein) by 50% and 51% and these inhibitors also decreased myocardial superoxide by 99% and 79%, respectively. Furthermore, 6-aminonicotinamide, a G6PD inhibitor, decreased myocardial superoxide production by 71%.

CONCLUSIONS:

These data suggest that high NAD(P)H oxidase, fueled by G6PD-derived NADPH, generates most of the superoxide in failing hearts of patients with ischemic cardiomyopathy. In addition, PKC-Src kinase signaling pathways seem to coordinate the activation of both G6PD and NAD(P)H oxidase in human cardiac muscle.

• Authors: Rakhee S Gupte, Venkataramana Vijay, Brian Marks, Robert J Levine, Hani N Sabbah, Michael S Wolin, Fabio A Recchia, Sachin A Gupte
• Journal: Journal of cardiac failure (J Card Fail) Vol. 13 Issue 6 Pg. 497-506 (Aug 2007) ISSN: 1532-8414 [Electronic] United States
• PMID: 17675065 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Biomarkers
• Superoxides
• Hydrogen Peroxide
• Glucosephosphate Dehydrogenase
• glucose-6-phosphate dehydrogenase A-
• NADPH Oxidases

Topics

• Biomarkers (metabolism)
• Blotting, Western
• Disease Progression
• Female
• Glucosephosphate Dehydrogenase (biosynthesis)
• Heart Failure (enzymology)
• Heart Ventricles (enzymology)
• Humans
• Hydrogen Peroxide (metabolism)
• Luminescent Measurements
• Male
• Middle Aged
• Myocardium (enzymology)
• NADPH Oxidases (biosynthesis)
• Oxidative Stress (physiology)
• Prognosis
• Severity of Illness Index
• Superoxides (metabolism)
• Up-Regulation (physiology)