Mechanisms of increased vascular superoxide production in human diabetes mellitus: role of NAD(P)H oxidase and endothelial nitric oxide synthase.
BACKGROUND
Increased superoxide production contributes to reduced vascular nitric oxide (NO) bioactivity and endothelial dysfunction in experimental models of diabetes. We characterized the sources and mechanisms underlying vascular superoxide production in human blood vessels from diabetic patients with coronary artery disease compared with nondiabetic patients.


RESULTS
Vascular superoxide production was quantified in both saphenous veins and internal mammary arteries from 45 diabetic and 45 matched nondiabetic patients undergoing coronary artery bypass surgery. NAD(P)H-dependent oxidases were important sources of vascular superoxide in both diabetic and nondiabetic patients, but both the activity of this enzyme system and the levels of NAD(P)H oxidase protein subunits (p22phox, p67phox, and p47phox) were significantly increased in diabetic veins and arteries. In nondiabetic vessels, endothelial NO synthase produced NO that scavenged superoxide. However, in diabetic vessels, the endothelium was an additional net source of superoxide production because of dysfunctional endothelial NO synthase that was corrected by intracellular tetrahydrobiopterin supplementation. Furthermore, increased superoxide production in diabetes was abrogated by the protein kinase C inhibitor chelerythrine.


CONCLUSIONS
These observations suggest important roles for NAD(P)H oxidases, endothelial NO synthase uncoupling, and protein kinase C signaling in mediating increased vascular superoxide production and endothelial dysfunction in human diabetes mellitus.
Guzik
Tomasz J
TJ
Department of Cardiovascular Medicine, University of Oxford, Oxford, UK.
Mussa
Shafi
S
Gastaldi
Daniela
D
Sadowski
Jerzy
J
Ratnatunga
Chandi
C
Pillai
Ravi
R
Channon
Keith M
KM
D001708:Biopterins / Q000031:analogs & derivatives*; D001808:Blood Vessels / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D003920:Diabetes Mellitus / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008323:Mammary Arteries / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D026901:Membrane Transport Proteins; D008875:Middle Aged; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009252:NADPH Dehydrogenase / Q000378:metabolism; D019255:NADPH Oxidases; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D010750:Phosphoproteins / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D012501:Saphenous Vein / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013481:Superoxides / Q000032:analysis / Q000378:metabolism*
D004791:Enzyme Inhibitors; D026901:Membrane Transport Proteins; D010750:Phosphoproteins; C079789:neutrophil cytosol factor 67K; D013481:Superoxides; D001708:Biopterins; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C086986:CYBA protein, human; C060505:neutrophil cytosolic factor 1; D009252:NADPH Dehydrogenase; D011493:Protein Kinase C; C003402:sapropterin