title: A key role for tetrahydrobiopterin-dependent endothelial NOS regulation in resistance arteries: studies in endothelial cell tetrahydrobiopterin-deficient mice.
abstract: The cofactor tetrahydrobiopterin (BH4) is a critical regulator of endothelial NOS (eNOS) function, eNOS-derived NO and ROS signalling in vascular physiology. To determine the physiological requirement for de novo endothelial cell BH4 synthesis for the vasomotor function of resistance arteries, we have generated a mouse model with endothelial cell-specific deletion of Gch1, encoding GTP cyclohydrolase 1 (GTPCH), an essential enzyme for BH4 biosynthesis, and evaluated BH4-dependent eNOS regulation, eNOS-derived NO and ROS generation.
  
  
  
  The reactivity of mouse second-order mesenteric arteries was assessed by wire myography. High performance liquid chromatography was used to determine BH4, BH2 and biopterin. Western blotting was used for expression analysis.
  
  
  
  Gch1fl/flTie2cre mice demonstrated reduced GTPCH protein and BH4 levels in mesenteric arteries. Deficiency in endothelial cell BH4 leads to eNOS uncoupling, increased ROS production and loss of NO generation in mesenteric arteries of Gch1fl/flTie2cre mice. Gch1fl/flTie2cre mesenteric arteries had enhanced vasoconstriction to U46619 and phenylephrine, which was abolished by L-NAME. Endothelium-dependent vasodilatations to ACh and SLIGRL were impaired in mesenteric arteries from Gch1fl/flTie2cre mice, compared with those from wild-type littermates. Loss of eNOS-derived NO-mediated vasodilatation was associated with increased eNOS-derived H2O2and cyclooxygenase-derived vasodilator in Gch1fl/flTie2cre mesenteric arteries.
  
  
  
  Endothelial cell Gch1 and BH4-dependent eNOS regulation play pivotal roles in maintaining vascular homeostasis in resistance arteries. Therefore, targeting vascular Gch1 and BH4 biosynthesis may provide a novel therapeutic target for the prevention and treatment of microvascular dysfunction in patients with cardiovascular disease.
authors.affiliation: British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, Oxford, UK.|Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
authors.forename: Surawee
authors.initials: S
authors.lastname: Chuaiphichai
authors.affiliation: British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, Oxford, UK.|Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Crabtree
authors.affiliation: British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, Oxford, UK.|Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
authors.forename: Eileen
authors.initials: E
authors.lastname: Mcneill
authors.affiliation: British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, Oxford, UK.|Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
authors.forename: Ashley B
authors.initials: AB
authors.lastname: Hale
authors.affiliation: British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, Oxford, UK.|Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
authors.forename: Lucy
authors.initials: L
authors.lastname: Trelfa
authors.affiliation: British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, Oxford, UK.|Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
authors.forename: Keith M
authors.initials: KM
authors.lastname: Channon
authors.affiliation: British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, Oxford, UK.|Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
authors.forename: Gillian
authors.initials: G
authors.lastname: Douglas
mesh_terms: D000818:Animals; D001708:Biopterins / Q000031:analogs & derivatives* / Q000172:deficiency / Q000378:metabolism; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D006136:GTP Cyclohydrolase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D008297:Male; D008638:Mesenteric Arteries / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D001708:Biopterins; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D006136:GTP Cyclohydrolase; C000597358:Gch1 protein, mouse; C003402:sapropterin