title: Therapeutic targeting of mitochondrial superoxide in hypertension.
abstract: BACKGROUND
  Superoxide (O2(-) ) has been implicated in the pathogenesis of many human diseases including hypertension; however, commonly used antioxidants have proven ineffective in clinical trials. It is possible that these agents are not adequately delivered to the subcellular sites of superoxide production.
  
  
  OBJECTIVE
  Because the mitochondria are important sources of reactive oxygen species, we postulated that mitochondrial targeting of superoxide scavenging would have therapeutic benefit.
  
  
  RESULTS
  In this study, we found that the hormone angiotensin (Ang II) increased endothelial mitochondrial superoxide production. Treatment with the mitochondria-targeted antioxidant mitoTEMPO decreased mitochondrial O2(-), inhibited the total cellular O2(-), reduced cellular NADPH oxidase activity, and restored the level of bioavailable NO. These effects were mimicked by overexpressing the mitochondrial MnSOD (SOD2), whereas SOD2 depletion with small interfering RNA increased both basal and Ang II-stimulated cellular O2(-). Treatment of mice in vivo with mitoTEMPO attenuated hypertension when given at the onset of Ang II infusion and decreased blood pressure by 30 mm Hg following establishment of both Ang II-induced and DOCA salt hypertension, whereas a similar dose of nontargeted TEMPOL was not effective. In vivo, mitoTEMPO decreased vascular O2(-), increased vascular NO production and improved endothelial-dependent relaxation. Interestingly, transgenic mice overexpressing mitochondrial SOD2 demonstrated attenuated Ang II-induced hypertension and vascular oxidative stress similar to mice treated with mitoTEMPO.
  
  
  CONCLUSIONS
  These studies show that mitochondrial O2(-) is important for the development of hypertension and that antioxidant strategies specifically targeting this organelle could have therapeutic benefit in this and possibly other diseases.
authors.affiliation: Division of Cardiology, Emory University School of Medicine, 1639 Pierce Dr, Atlanta, GA 30322, USA.
authors.forename: Anna E
authors.initials: AE
authors.lastname: Dikalova
authors.forename: Alfiya T
authors.initials: AT
authors.lastname: Bikineyeva
authors.forename: Klaudia
authors.initials: K
authors.lastname: Budzyn
authors.forename: Rafal R
authors.initials: RR
authors.lastname: Nazarewicz
authors.forename: Louise
authors.initials: L
authors.lastname: McCann
authors.forename: William
authors.initials: W
authors.lastname: Lewis
authors.forename: David G
authors.initials: DG
authors.lastname: Harrison
authors.forename: Sergey I
authors.initials: SI
authors.lastname: Dikalov
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage*; D002417:Cattle; D002478:Cells, Cultured; D003497:Cyclic N-Oxides / Q000008:administration & dosage; D016503:Drug Delivery Systems / Q000379:methods*; D042783:Endothelial Cells; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000201:enzymology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D013482:Superoxide Dismutase / Q000096:biosynthesis*; D013481:Superoxides / Q000378:metabolism; D000099156:Superoxide Dismutase 2
chemical_list: D000975:Antioxidants; D003497:Cyclic N-Oxides; D013482:Superoxide Dismutase; D013481:Superoxides; D000099156:Superoxide Dismutase 2; C003959:TEMPO
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