title: Endogenous vascular hydrogen peroxide regulates arteriolar tension in vivo.
abstract: BACKGROUND
  Although many studies suggested direct vasomotor effects of hydrogen peroxide (H2O2) in vitro, little is known about the vasomotor effects of H2O2 in vivo.
  
  
  RESULTS
  We have generated mice overexpressing human catalase driven by the Tie-2 promoter to specifically target this transgene to the vascular tissue. Vessels of these mice (cat++) expressed significantly higher levels of catalase mRNA, protein, and activity. The overexpression was selective for vascular tissue, as evidenced by immunohistochemistry in specimens of aorta, heart, lung, and kidney. Quantification of reactive oxygen species by fluorescence signals in cat++ versus catalase-negative (catn) mice showed a strong decrease in aortic endothelium and left ventricular myocardium but not in leukocytes. Awake male cat++ at 3 to 4 months of age had a significantly lower systolic blood pressure (sBP, 102.7+/-2.2 mm Hg, n=10) compared with their transgene-negative littermates (catn, 115.6+/-2.5 mm Hg, P=0.0211) and C57BL/6 mice (118.4+/-3.06 mm Hg, n=6). Treatment with the catalase inhibitor aminotriazole increased sBP of cat++ to 117.3+/-4.3 mm Hg (P=0.0345), while having no effect in catn (118.4+/-2.4 mm Hg, n=4, P>0.05). In contrast, treatment with the NO-synthase inhibitor nitro-L-arginine methyl ester (100 mg.kg BW(-1).d(-1)) increased sBP in cat++ and C57Bl/6 to a similar extent. Likewise, phosphorylation of vasodilator-stimulated phosphoprotein in skeletal muscle, left ventricular myocardium, and lung was identical in cat++ and catn. Endothelium- and NO-dependent aortic vasodilations were unchanged in cat++. Aortic KCl contractions were significantly lower in cat++ and exogenous H2O2 (10 micromol/L)-induced vasoconstriction.
  
  
  CONCLUSIONS
  These data suggest that endogenous H2O2 may act as a vasoconstrictor in resistance vessels and contribute to the regulation of blood pressure.
authors.affiliation: Institut für Pharmakologie und Klinische Pharmakologie, Heinrich-Heine-Universität, 40225 Düsseldorf, Germany. kojda@uni-duesseldorf.de
authors.forename: Tatsiana
authors.initials: T
authors.lastname: Suvorava
authors.forename: Nadine
authors.initials: N
authors.lastname: Lauer
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kumpf
authors.forename: Ralf
authors.initials: R
authors.lastname: Jacob
authors.forename: Wilfried
authors.initials: W
authors.lastname: Meyer
authors.forename: Georg
authors.initials: G
authors.lastname: Kojda
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000502:physiology; D001160:Arterioles / Q000187:drug effects / Q000502:physiology*; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014664:Vasodilation
chemical_list: D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D006861:Hydrogen Peroxide; D002374:Catalase; D052250:Nitric Oxide Synthase Type III