Is hydrogen peroxide an EDHF in human radial arteries?
In human radial arteries, a nitric oxide/prostanoid-independent mechanism that has the pharmacological characteristics of an EDHF contributes to endothelium-dependent relaxation. H2O2 can act as an EDHF in some vascular beds. We examined the hypothesis that endogenously produced H2O2 mediated the nitric oxide/prostanoid-independent relaxation to carbachol in radial arteries obtained from patients undergoing coronary artery bypass surgery. Superoxide levels, measured by chemiluminescence, were similar in radial and internal mammary arteries, but immunohistochemical staining for Cu/Zn superoxide dismutase (SOD) was lower in endothelium from radial arteries. In organ chamber studies, neither addition of catalase nor addition of SOD to the bathing fluid modified nitric oxide/prostanoid-independent relaxations to carbachol in radial arteries. However, nitric oxide-dependent vasorelaxation was enhanced in the presence of SOD. Thus the nitric oxide/prostanoid-independent relaxation to carbachol is not due to H2O2 and, unlike nitric oxide-mediated vasorelaxation, is not attenuated by superoxide. Blood vessels showing EDHF-mediated relaxations resistant to oxidative stress may provide favorable outcomes in revascularization surgery.
Hamilton
C A
CA
Department of Medicine and Therapeutics, Western Infirmary, Glasgow G11 6NT, United Kingdom. cah1p@clinmed.gla.ac.uk
McPhaden
A R
AR
Berg
G
G
Pathi
V
V
Dominiczak
A F
AF
D001685:Biological Factors / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology; D002374:Catalase / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008323:Mammary Arteries / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010477:Perfusion; D017534:Radial Artery / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects
D001685:Biological Factors; D018679:Cholinergic Agonists; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; C067410:endothelium-dependent hyperpolarization factor; D013481:Superoxides; D002217:Carbachol; D006861:Hydrogen Peroxide; D002374:Catalase; D019001:Nitric Oxide Synthase; D013482:Superoxide Dismutase; D019331:NG-Nitroarginine Methyl Ester