Antioxidant vitamins C and E ameliorate hyperglycaemia-induced oxidative stress in coronary endothelial cells.
OBJECTIVE
Vitamins C and E have protective features in many disease states associated with enhanced oxidative stress. The aim of this study was to investigate whether vitamin(s) C and/or E modulate hyperglycaemia-induced oxidative stress by regulating enzymatic activities of prooxidant, i.e. NAD(P)H oxidase and/or antioxidant enzymes, namely endothelial nitric oxide synthase (eNOS), superoxide dismutase, catalase and glutathione peroxidase, using coronary microvascular endothelial cells (CMEC).


METHODS
CMEC were cultured under normal (5.5 mM) or high glucose (22 mM) concentrations for 7 days. The enzyme activities were determined by specific assays. The levels of O(2) (-) and nitrite were measured by cytochrome c reduction and Griess assays respectively.


RESULTS
Hyperglycaemia did not alter eNOS activity or overall nitrite generation, an index of NO production. However, it increased NAD(P)H oxidase and antioxidant enzyme activities (p < 0.05). Specific inhibitors of NAD(P)H oxidase, i.e. phenylarsine oxide (0.1-3 microm) and 4-(2-aminoethyl)benzenesulfonyl fluoride (5-100 microm) and vitamins C and E (0.1-1 microm) significantly reduced prooxidant and antioxidant enzyme activities in CMEC exposed to hyperglycaemia (p < 0.01). The differences in enzyme activities were independent of increases in osmolarity generated by high glucose levels as investigated by using equimolar concentrations of mannitol in parallel experiments.


CONCLUSIONS
Vitamins C and E may protect CMEC against hyperglycaemia-induced oxidative stress by concomitantly regulating prooxidant and antioxidant enzyme activities.
Department of Medicine, Institute of Clinical Science Block B, Queen's University Belfast, Belfast BT12 6BJ, UK.
S
S
Ulker
D
D
McMaster
P P
PP
McKeown
U
U
Bayraktutan
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000187:drug effects / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019255:NADPH Oxidases; D019001:Nitric Oxide Synthase / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D014810:Vitamin E / Q000494:pharmacology*
D000975:Antioxidants; D004791:Enzyme Inhibitors; D009573:Nitrites; D016877:Oxidants; D017382:Reactive Oxygen Species; D014810:Vitamin E; D019001:Nitric Oxide Synthase; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D005947:Glucose; D001205:Ascorbic Acid