title: The effect of prolonged dietary nitrate supplementation on atherosclerosis development.
abstract: BACKGROUND
  Short term dietary nitrate or nitrite supplementation has nitric oxide (NO)-mediated beneficial effects on blood pressure and inflammation and reduces mitochondrial oxygen consumption, possibly preventing hypoxia. As these processes are implicated in atherogenesis, dietary nitrate was hypothesized to prevent plaque initiation, hypoxia and inflammation.
  
  
  OBJECTIVE
  Study prolonged nitrate supplementation on atherogenesis, hypoxia and inflammation in low density lipoprotein receptor knockout mice (LDLr(-/-)).
  
  
  METHODS
  LDLr(-/-) mice were administered sodium-nitrate or equimolar sodium-chloride in drinking water alongside a western-type diet for 14 weeks to induce atherosclerosis. Plasma nitrate, nitrite and hemoglobin-bound nitric oxide were measured by chemiluminescence and electron parametric resonance, respectively.
  
  
  RESULTS
  Plasma nitrate levels were elevated after 14 weeks of nitrate supplementation (NaCl: 40.29 ± 2.985, NaNO3: 78.19 ± 6.837, p < 0.0001). However, prolonged dietary nitrate did not affect systemic inflammation, hematopoiesis, erythropoiesis and plasma cholesterol levels, suggesting no severe side effects. Surprisingly, neither blood pressure, nor atherogenesis were altered. Mechanistically, plasma nitrate and nitrite were elevated after two weeks (NaCl: 1.0 ± 0.2114, NaNO3: 3.977 ± 0.7371, p < 0.0001), but decreased over time (6, 10 and 14 weeks). Plasma nitrite levels even reached baseline levels at 14 weeks (NaCl: 0.7188 ± 0.1072, NaNO3: 0.9723 ± 0.1279 p = 0.12). Also hemoglobin-bound NO levels were unaltered after 14 weeks. This compensation was not due to altered eNOS activity or conversion into peroxynitrite and other RNI, suggesting reduced nitrite formation or enhanced nitrate/nitrite clearance.
  
  
  CONCLUSIONS
  Prolonged dietary nitrate supplementation resulted in compensation of nitrite and NO levels and did not affect atherogenesis or exert systemic side effects.
authors.affiliation: Department Pathology, CARIM, MUMC, Maastricht, The Netherlands.
authors.forename: Elke
authors.initials: E
authors.lastname: Marsch
authors.affiliation: Department Pathology, CARIM, MUMC, Maastricht, The Netherlands.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Theelen
authors.affiliation: Department Pharmacology, CARIM, Maastricht University, Maastricht, The Netherlands.
authors.forename: Ben J A
authors.initials: BJ
authors.lastname: Janssen
authors.affiliation: Department Toxicogenomics, Maastricht University, Maastricht, The Netherlands.
authors.forename: Jacco J
authors.initials: JJ
authors.lastname: Briede
authors.affiliation: Department Toxicology, Maastricht University, Maastricht, The Netherlands.
authors.forename: Guido R
authors.initials: GR
authors.lastname: Haenen
authors.affiliation: NUTRIM, School for Nutrition, Toxicology and Metabolism, MUMC, Maastricht, The Netherlands.
authors.forename: Joan M G
authors.initials: JM
authors.lastname: Senden
authors.affiliation: NUTRIM, School for Nutrition, Toxicology and Metabolism, MUMC, Maastricht, The Netherlands.
authors.forename: Lucas J C
authors.initials: LJ
authors.lastname: van Loon
authors.affiliation: Department Surgery/Intensive Care Medicine, MUMC, Maastricht, The Netherlands.
authors.forename: Martijn
authors.initials: M
authors.lastname: Poeze
authors.affiliation: Department of Clinical Genetics, MUMC, Maastricht, The Netherlands.
authors.forename: Jörgen
authors.initials: J
authors.lastname: Bierau
authors.affiliation: Department Pathology, CARIM, MUMC, Maastricht, The Netherlands; Department Molecular Genetics, CARIM, Maastricht University, Maastricht, The Netherlands; Department Medical Biochemistry, AMC, Amsterdam, The Netherlands.
authors.forename: Marion J
authors.initials: MJ
authors.lastname: Gijbels
authors.affiliation: Department Pathology, AMC, Amsterdam, The Netherlands.
authors.forename: Mat J A P
authors.initials: MJ
authors.lastname: Daemen
authors.affiliation: Department Pathology, CARIM, MUMC, Maastricht, The Netherlands. Electronic address: judith.sluimer@maastrichtuniversity.nl.
authors.forename: Judith C
authors.initials: JC
authors.lastname: Sluimer
mesh_terms: D000818:Animals; D050197:Atherosclerosis / Q000209:etiology* / Q000378:metabolism; D019587:Dietary Supplements / Q000633:toxicity*; D004195:Disease Models, Animal; D051379:Mice; D018345:Mice, Knockout; D009573:Nitrites / Q000633:toxicity*; D009589:Nitrogen Oxides / Q000378:metabolism
chemical_list: D009573:Nitrites; D009589:Nitrogen Oxides
keywords: Atherosclerosis; Blood pressure; Hypoxia; Inflammation; Nitrate