title: Role of endothelium/nitric oxide in atypical beta-adrenoceptor-mediated relaxation in rat isolated aorta.
abstract: The role of endothelium in the modulation of classical and atypical beta-adrenoceptor-mediated vasorelaxation was investigated in ring preparations of rat isolated thoracic aorta. Rings were pre-constricted with a sub-maximal concentration of noradrenaline (1 microM) and relaxant responses to cumulative concentrations of beta-adrenoceptor agonists obtained. Endothelium removal or pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME, 100 microM) or 1H-[1,2,4] oxadiazolol[4,3,-a] quinoxalin-1-one (ODQ, 10 microM) significantly reduced the relaxant effects of isoprenaline, but had less effect on relaxant responses to the atypical beta-adrenoceptor agonist, (+/-)-4-(3-t-butylamino-2-hydroxypropoxy)-benzimidazol-2-one hydrochloride (CGP 12177A). Sodium nitroprusside (3 nM) shifted the isoprenaline concentration-response curve to the left and restored the attenuated responses in the presence of L-NAME back to control levels. Sodium nitroprusside had little effect on the CGP 12177A concentration-response curve. The results show that the endothelium/nitric oxide (NO) pathway modulates beta-adrenoceptor-mediated vasorelaxation in rat aorta and that classical beta-adrenoceptors are modulated to a greater extent than atypical beta-adrenoceptors.
authors.affiliation: School of Biological and Biomedical Sciences, Glasgow Caledonian University, G4 0BA, Glasgow, UK.
authors.forename: L
authors.initials: L
authors.lastname: Brawley
authors.forename: A M
authors.initials: AM
authors.lastname: Shaw
authors.forename: A
authors.initials: A
authors.lastname: MacDonald
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000502:physiology*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010069:Oxadiazoles / Q000494:pharmacology; D010642:Phenoxyacetates / Q000494:pharmacology; D050198:Phenoxypropanolamines; D010648:Phenylacetates / Q000494:pharmacology; D010869:Pindolol / Q000031:analogs & derivatives / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
chemical_list: C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D010069:Oxadiazoles; D010642:Phenoxyacetates; D050198:Phenoxypropanolamines; D010648:Phenylacetates; D011412:Propanolamines; D011810:Quinoxalines; D011943:Receptors, Adrenergic, beta; C413933:ZM 215001; D009599:Nitroprusside; D009569:Nitric Oxide; C047975:cyanopindolol; D011433:Propranolol; D010869:Pindolol; D007545:Isoproterenol; C102383:talibegron hydrochloride; C033394:CGP 12177; D019331:NG-Nitroarginine Methyl Ester; D009638:Norepinephrine