title: Selective impairment of blood pressure reduction by endothelial nitric oxide synthase dimer destabilization in mice.
abstract: Endothelial dysfunction and oxidative stress are associated with hypertension but whether endothelial superoxide may play a role in the early development of essential hypertension remains uncertain. We investigated whether endothelial nitric oxide synthase (eNOS)-derived endothelial oxidative stress is involved in the regulation of SBP.
  
  
  
  Wild-type eNOS [mice with endothelium-specific overexpression of bovine endothelial NO-synthase (eNOS-Tg)] or a novel dimer-destabilized eNOS-mutant harboring a partially disrupted zinc-finger [mice with endothelium-specific overexpression of destabilized bovine eNOS destabilized by replacement of Cys 101 to Ala (C101A-eNOS-Tg)] was introduced in C57BL/6 in an endothelial-specific manner. Mice were monitored for aortic endothelium-dependent relaxation, SBP, levels of superoxide and several posttranslational modifications indicating activity and/or increased vascular oxidative stress. Some groups of mice underwent voluntary exercise training for 4 weeks or treatment with the superoxide dismutase mimetic Tempol.
  
  
  
  C101A-eNOS-Tg showed significantly increased superoxide generation, protein-tyrosine-nitration and eNOS-tyrosine-nitration, eNOS-S-glutathionylation, eNOS phosphorylation and AMP kinase-α phosphorylation at Thr172 in aorta, skeletal muscle, left ventricular myocardium and lung as compared with eNOS-Tg and wild-type controls. Exercise training increased phosphorylation of eNOS at Ser and AMP kinase-α in wild-type. These physiologic adaptations were absent in C101A-eNOS-Tg. Maximal aortic endothelium-dependent relaxation was similar in all strains. C101A-eNOS-Tg displayed normal SBP despite higher levels of eNOS, whereas eNOS-Tg showed significant hypotension. Tempol completely reversed the occurring protein modifications and significantly reduced SBP in C101A-eNOS-Tg but not in wild-type.
  
  
  
  Oxidative stress generated by endothelial-specific expression of genetically destabilized C101A-eNOS selectively prevents SBP-reducing activity of vascular eNOS, while having no effect on aortic endothelium-dependent relaxation. These data suggest that oxidative stress in microvascular endothelium may play a role for the development of essential hypertension.
authors.affiliation: aInstitute of Pharmacology and Clinical Pharmacology bCardiovascular Research Laboratory, Division of Cardiology, Pulmonology and Vascular Medicine, University Hospital, Heinrich-Heine-University, Düsseldorf, Germany.
authors.forename: Tatsiana
authors.initials: T
authors.lastname: Suvorava
authors.forename: Stephanie
authors.initials: S
authors.lastname: Pick
authors.forename: Georg
authors.initials: G
authors.lastname: Kojda
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000235:genetics* / Q000502:physiology*; D002417:Cattle; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation / Q000235:genetics / Q000502:physiology; D052250:Nitric Oxide Synthase Type III / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology; D010766:Phosphorylation; D055550:Protein Stability
chemical_list: D052250:Nitric Oxide Synthase Type III