title: Elevated endothelial nitric oxide bioactivity and resistance to angiotensin-dependent hypertension in 12/15-lipoxygenase knockout mice.
abstract: 12/15-Lipoxygenase (12/15-LOX) plays a pathogenic role in atherosclerosis. To characterize whether 12/15-LOX also contributes to endothelial dysfunction and hypertension, regulation of vessel tone and angiotensin II (ang II) responses were characterized in mice deficient in 12/15-LOX. There was a twofold increase in the magnitude of l-nitroarginine-methyl ester-inhibitable, acetylcholine-dependent relaxation or phenylephrine-dependent constriction in aortic rings isolated from 12/15-LOX(-/-) mice. Plasma NO metabolites and aortic endothelial NO synthase (eNOS) expression were also elevated twofold. Angiotensin II failed to vasoconstrict 12/15-LOX(-/-) aortic rings in the absence of L-nitroarginine-methyl ester, and ang II impaired acetylcholine-induced relaxation in wild-type, but not 12/15-LOX(-/-) rings. In vivo, 12/15-LOX(-/-) mice had similar basal systolic blood pressure measurements to wild type, however, blood pressure elevations in response to ang II infusion (1.1 mg/kg/day) were significantly attenuated (maximal pressure, 143.4 +/- 4 mmHg versus 122.1 +/- 5.3 mmHg for wild type and 12/15-LOX(-/-), respectively). In contrast, vascular hypertrophic responses to ang II, and ang II type 1 receptor (AT1-R) expression were similar in both strains. This study shows that 12/15-LOX(-/-) mice have increased NO biosynthesis and impaired ang II-dependent vascular responses in vitro and in vivo, suggesting that 12/15-LOX signaling contributes to impaired NO bioactivity in vascular disease in vivo.
authors.affiliation: Department of Medical Biochemistry and Immunology, University of Wales College of Medicine, Heath Park, Cardiff CF14 4XN, UK.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Anning
authors.forename: Barbara
authors.initials: B
authors.lastname: Coles
authors.forename: Alexandra
authors.initials: A
authors.lastname: Bermudez-Fajardo
authors.forename: Patricia E M
authors.initials: PE
authors.lastname: Martin
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Levison
authors.forename: Stanley L
authors.initials: SL
authors.lastname: Hazen
authors.forename: Colin D
authors.initials: CD
authors.lastname: Funk
authors.forename: Hartmut
authors.initials: H
authors.lastname: Kühn
authors.forename: Valerie B
authors.initials: VB
authors.lastname: O'Donnell
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000809:Angiotensins / Q000378:metabolism*; D000818:Animals; D001011:Aorta / Q000378:metabolism; D001092:Arachidonate 12-Lipoxygenase / Q000235:genetics*; D001093:Arachidonate 15-Lipoxygenase / Q000235:genetics*; D001794:Blood Pressure; D001835:Body Weight; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D006973:Hypertension / Q000201:enzymology* / Q000473:pathology; D007150:Immunohistochemistry; D050356:Lipid Metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D015398:Signal Transduction; D013997:Time Factors
chemical_list: C475064:12-15-lipoxygenase; D000809:Angiotensins; D009569:Nitric Oxide; D001092:Arachidonate 12-Lipoxygenase; D001093:Arachidonate 15-Lipoxygenase; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester
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