title: β3 Adrenergic Stimulation Restores Nitric Oxide/Redox Balance and Enhances Endothelial Function in Hyperglycemia.
abstract: BACKGROUND
  Perturbed balance between NO and O2 (•-). (ie, NO/redox imbalance) is central in the pathobiology of diabetes-induced vascular dysfunction. We examined whether stimulation of β3 adrenergic receptors (β3 ARs), coupled to endothelial nitric oxide synthase (eNOS) activation, would re-establish NO/redox balance, relieve oxidative inhibition of the membrane proteins eNOS and Na(+)-K(+) (NK) pump, and improve vascular function in a new animal model of hyperglycemia.
  
  
  RESULTS
  We established hyperglycemia in male White New Zealand rabbits by infusion of S961, a competitive high-affinity peptide inhibitor of the insulin receptor. Hyperglycemia impaired endothelium-dependent vasorelaxation by "uncoupling" of eNOS via glutathionylation (eNOS-GSS) that was dependent on NADPH oxidase activity. Accordingly, NO levels were lower while O2 (•-) levels were higher in hyperglycemic rabbits. Infusion of the β3 AR agonist CL316243 (CL) decreased eNOS-GSS, reduced O2 (•-), restored NO levels, and improved endothelium-dependent relaxation. CL decreased hyperglycemia-induced NADPH oxidase activation as suggested by co-immunoprecipitation experiments, and it increased eNOS co-immunoprecipitation with glutaredoxin-1, which may reflect promotion of eNOS de-glutathionylation by CL. Moreover, CL reversed hyperglycemia-induced glutathionylation of the β1 NK pump subunit that causes NK pump inhibition, and improved K(+)-induced vasorelaxation that reflects enhancement in NK pump activity. Lastly, eNOS-GSS was higher in vessels of diabetic patients and was reduced by CL, suggesting potential significance of the experimental findings in human diabetes.
  
  
  CONCLUSIONS
  β3 AR activation restored NO/redox balance and improved endothelial function in hyperglycemia. β3 AR agonists may confer protection against diabetes-induced vascular dysfunction.
authors.affiliation: North Shore Heart Research Group, Kolling Institute, University of Sydney, Australia University of Sydney Medical School Foundation, Sydney, Australia Columbia University Medical Center, New York, NY.
authors.forename: Keyvan
authors.initials: K
authors.lastname: Karimi Galougahi
authors.affiliation: North Shore Heart Research Group, Kolling Institute, University of Sydney, Australia.
authors.forename: Chia-Chi
authors.initials: CC
authors.lastname: Liu
authors.affiliation: North Shore Heart Research Group, Kolling Institute, University of Sydney, Australia.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Garcia
authors.affiliation: School of Medicine, University of Sydney, Australia Heart Research Institute, Sydney, Australia.
authors.forename: Carmine
authors.initials: C
authors.lastname: Gentile
authors.affiliation: North Shore Heart Research Group, Kolling Institute, University of Sydney, Australia.
authors.forename: Natasha A
authors.initials: NA
authors.lastname: Fry
authors.affiliation: North Shore Heart Research Group, Kolling Institute, University of Sydney, Australia.
authors.forename: Elisha J
authors.initials: EJ
authors.lastname: Hamilton
authors.affiliation: Heart Research Institute, Sydney, Australia.
authors.forename: Clare L
authors.initials: CL
authors.lastname: Hawkins
authors.affiliation: North Shore Heart Research Group, Kolling Institute, University of Sydney, Australia Department of Cardiology, Royal North Shore Hospital, Sydney, Australia gemma.figtree@sydney.edu.au.
authors.forename: Gemma A
authors.initials: GA
authors.lastname: Figtree
mesh_terms: D058667:Adrenergic beta-3 Receptor Agonists / Q000494:pharmacology*; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000188:drug therapy* / Q000201:enzymology / Q000503:physiopathology; D003925:Diabetic Angiopathies / Q000139:chemically induced / Q000201:enzymology / Q000503:physiopathology / Q000517:prevention & control*; D004149:Dioxoles / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000503:physiopathology; D004789:Enzyme Activation; D005978:Glutathione / Q000378:metabolism; D006943:Hyperglycemia / Q000139:chemically induced / Q000188:drug therapy* / Q000201:enzymology / Q000503:physiopathology; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D008297:Male; D019255:NADPH Oxidases / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D010455:Peptides; D011817:Rabbits; D022702:Receptors, Adrenergic, beta-3 / Q000187:drug effects* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors
chemical_list: D058667:Adrenergic beta-3 Receptor Agonists; D001786:Blood Glucose; D004149:Dioxoles; D007004:Hypoglycemic Agents; D010455:Peptides; D022702:Receptors, Adrenergic, beta-3; C532752:S961 peptide; D013481:Superoxides; C076126:disodium (R,R)-5-(2-((2-(3-chlorophenyl)-2-hydroxyethyl)-amino)propyl)-1,3-benzodioxole-2,3-dicarboxylate; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D019255:NADPH Oxidases; D000254:Sodium-Potassium-Exchanging ATPase; D005978:Glutathione
keywords: endothelial dysfunction; endothelial nitric oxide synthase; hyperglycemia; oxidative stress; β3 adrenergic receptors