High pressure induces superoxide production in isolated arteries via protein kinase C-dependent activation of NAD(P)H oxidase.
BACKGROUND
Oxidative stress seems to be present in all forms of hypertension. Thus, we tested the hypothesis that high intraluminal pressure (Pi) itself, by activating vascular oxidases, elicits increased superoxide (O2*-) production interfering with flow-induced dilation.


RESULTS
Isolated, cannulated rat femoral arterial branches were exposed in vitro (for 30 minutes) to normal Pi (80 mm Hg) or high Pi (160 mm Hg). High Pi significantly increased vascular O2*- production (as measured by lucigenin chemiluminescence and ethidium bromide fluorescence) and impaired endothelium-dependent dilations to flow; these effects could be reversed by superoxide dismutase. Administration of the NAD(P)H oxidase inhibitor diphenyleneiodonium, apocynin, the protein kinase C (PKC) inhibitor chelerythrine or staurosporin or the removal of extracellular Ca2+ during high Pi treatment prevented the increases in O2*- production, whereas administration of losartan or captopril had no effect. High Pi resulted in significant increases in intracellular Ca2+ ([Ca2+]i) in the vascular wall (fura 2 fluorescence) and phosphorylation of PKCalpha (Western blotting). The PKC activator phorbol myristate acetate significantly increased vascular O2*- production, which was inhibited by superoxide dismutase, diphenyleneiodonium, chelerythrine, or removal of extracellular Ca2+. Both high Pi and phorbol myristate acetate increased the phosphorylation of the NAD(P)H oxidase subunit p47phox.


CONCLUSIONS
High Pi itself elicits arterial O2.- production, most likely by PKC-dependent activation of NAD(P)H oxidase, thus providing a potential explanation for the presence of oxidative stress and endothelial dysfunction in various forms of hypertension and the vasculoprotective effect of antihypertensive agents of different mechanisms of action.
Ungvari
Zoltan
Z
Department of Physiology, New York Medical College, Valhalla, NY 10595, USA.
Csiszar
Anna
A
Huang
An
A
Kaminski
Pawel M
PM
Wolin
Michael S
MS
Koller
Akos
A
D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005263:Femoral Artery / Q000187:drug effects / Q000503:physiopathology*; D005456:Fluorescent Dyes; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019255:NADPH Oxidases; D010088:Oxidoreductases / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D010750:Phosphoproteins; D013481:Superoxides; D010088:Oxidoreductases; D013482:Superoxide Dismutase; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D011493:Protein Kinase C; D002118:Calcium