title: Nitroxyl (HNO) suppresses vascular Nox2 oxidase activity.
abstract: Nox2 oxidase activity underlies the oxidative stress and vascular dysfunction associated with several vascular-related diseases. We have reported that nitric oxide (NO) decreases reactive oxygen species production by endothelial Nox2. This study tested the hypothesis that nitroxyl (HNO), the redox sibling of NO, also suppresses vascular Nox2 oxidase activity. Specifically, we examined the influence of two well-characterized HNO donors, Angeli's salt and isopropylamine NONOate (IPA/NO), on Nox2-dependent responses to angiotensin II (reactive oxygen species production and vasoconstriction) in mouse cerebral arteries. Angiotensin II (0.1μmol/L)-stimulated superoxide (measured by lucigenin-enhanced chemiluminescence) and hydrogen peroxide (Amplex red fluorescence) levels in cerebral arteries (pooled basilar and middle cerebral (MCA)) from wild-type (WT) mice were ~60% lower (P<0.05) in the presence of either Angeli's salt (1μmol/L) or IPA/NO (1μmol/L). Similarly, phorbyl 12,13-dibutyrate (10μmol/L; Nox2 activator)-stimulated hydrogen peroxide levels were ~40% lower in the presence of IPA/NO (1μmol/L; P<0.05). The ability of IPA/NO to decrease superoxide levels was reversible and abolished by the HNO scavenger l-cysteine (3mmol/L; P<0.05), but was unaffected by hydroxocobalamin (100μmol/L; NO scavenger), ODQ (10μmol/L; soluble guanylyl cyclase (sGC) inhibitor), or Rp-8-pCPT-cGMPS (10μmol/L; cyclic guanosine monophosphate (cGMP)-dependent protein kinase inhibitor). Angiotensin II-stimulated superoxide was substantially less in arteries from Nox2-deficient (Nox2(-/y)) versus WT mice (P<0.05). In contrast to WT, IPA/NO (1μmol/L) had no effect on superoxide levels in arteries from Nox2(-/y) mice. Finally, angiotensin II (1-1000μmol/L)-induced constriction of WT MCA was virtually abolished by IPA/NO (1μmol/L), whereas constrictor responses to either the thromboxane A2 mimetic U46619 (1-100 nmol/L) or high potassium (122.7mmol/L) were unaffected. In conclusion, HNO suppresses vascular Nox2 oxidase activity via a sGC-cGMP-independent pathway. Thus, HNO donors might be useful therapeutic agents to limit and/or prevent Nox2-dependent vascular dysfunction.
authors: Vascular Biology and Immunopharmacology Group, Department of Pharmacology, Monash University, Melbourne, VIC 3800, Australia.
authors: Alyson A
authors: AA
authors: Miller
authors: Kate F
authors: KF
authors: Maxwell
authors: Sophocles
authors: S
authors: Chrissobolis
authors: Michelle L
authors: ML
authors: Bullen
authors: Jacqueline M
authors: JM
authors: Ku
authors: T
authors: T
authors: Michael De Silva
authors: Stavros
authors: S
authors: Selemidis
authors: Elizabeth U
authors: EU
authors: Hooker
authors: Grant R
authors: GR
authors: Drummond
authors: Christopher G
authors: CG
authors: Sobey
authors: Barbara K
authors: BK
authors: Kemp-Harper
mesh_terms: D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D002536:Cerebral Arteries / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D006834:Hydrazines / Q000008:administration & dosage* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051379:Mice; D058990:Molecular Targeted Therapy; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D009589:Nitrogen Oxides / Q000378:metabolism*; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D014652:Vascular Diseases / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology
chemical_list: C507406:1-isopropyldiazen-1-ium-1,2-diolate; D006834:Hydrazines; D008562:Membrane Glycoproteins; D009589:Nitrogen Oxides; D017382:Reactive Oxygen Species; D013481:Superoxides; D000804:Angiotensin II; D009569:Nitric Oxide; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C039900:nitroxyl