title: Analysis of tert-butyl hydroperoxide induced constrictions of perfused vascular beds in vitro.
abstract: tert-Butyl hydroperoxide (t-BOOH), an inducer of oxidative stress in vitro, elicits constrictor responses of the isolated, rat kidney and mesenteric arteries perfused (5 ml/min) with physiological salt solutions (PSS) at 37 degrees C gassed with carbogen. We hypothesized that generation of superoxide anions (O(2)(-)) accounts for these responses. We assessed responses to t-BOOH in preparations with/without endothelium, and in the absence/presence of antioxidant compounds, catalase and tempol, scavengers of hydroxyl (OH(-)) radical and O(2)(-), respectively. t-BOOH (0.01-50 micromol) induced (expressed as % of 50 micromol KCl vasoconstriction) were abolished by endothelium denudation, perfusion with Ca(2+)-free PSS and by nifedipine, (1 nM). Infusion of t-BOOH (0.1 microM) did not significantly (P > 0.05) affect phenylepherine E(max) in the mesenteric arteries, however it reduced phenylepherine E(max) responses in the kidney from 94.9 +/- 3.9 % to 64.7 +/- 4.7 %. Nitroblue tetrazolium, as well as alpha-phenyl N-tert-butyl nitrone, at 100 microM, but not catalase (500 IU) significantly attenuated t-BOOH (10 micromol) vasoconstrictor responses. Tempol (100 microM), a membrane permeable antioxidant, also significantly reduced t-BOOH (10 micromol) responses from 17.0 +/- 1.9 % (control) to 9.6 +/- 0.5 % (+tempol) in the mesenteric arteries and from 40.4 +/- 4.2 % (control) to 20.7 +/- 1.5 % (+tempol) in the kidney. Our data suggest that t-BOOH elicits vasoconstriction via two distinct mechanisms: (i) increased influx of extracellular Ca(2+), and (ii) generation of free radicals including O(2)(-) anions.
authors.affiliation: Department of Physiology and Biophysics, Health Sciences Center, University of Louisville, Louisville KY 40292, USA.
authors.forename: Sunday O
authors.initials: SO
authors.lastname: Awe
authors.forename: Ayotunde S O
authors.initials: AS
authors.lastname: Adeagbo
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002374:Catalase / Q000494:pharmacology; D003497:Cyclic N-Oxides; D004730:Endothelium, Vascular / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D066298:In Vitro Techniques; D007668:Kidney / Q000098:blood supply*; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009580:Nitroblue Tetrazolium / Q000494:pharmacology; D009589:Nitrogen Oxides / Q000494:pharmacology; D018384:Oxidative Stress; D010656:Phenylephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D020122:tert-Butylhydroperoxide / Q000494:pharmacology*
chemical_list: D003497:Cyclic N-Oxides; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D009589:Nitrogen Oxides; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D009580:Nitroblue Tetrazolium; C029217:phenyl-N-tert-butylnitrone; D011189:Potassium Chloride; D020122:tert-Butylhydroperoxide; D002374:Catalase; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester