title: Quercetin and its major metabolites selectively modulate cyclic GMP-dependent relaxations and associated tolerance in pig isolated coronary artery.
abstract: OBJECTIVE
  Quercetin is a major flavonoid that contributes to the reduced risk of cardiovascular disease associated with dietary ingestion of fruits and vegetables. We have pharmacologically characterized the effect of quercetin, and its sulphate and glucuronide metabolites, on vasoconstrictor and vasodilator responses in the porcine isolated coronary artery.
  
  
  METHODS
  Segments of the porcine coronary artery were prepared for either isometric tension recording or determination of cyclic GMP content. The effect of quercetin and metabolites on submaximal responses to U46619 was examined in the presence and absence of substance P, bradykinin, forskolin, sodium nitroprusside (SNP) and glyceryl trinitrate (GTN).
  
  
  RESULTS
  Quercetin and quercetin 3'-sulphate inhibited endothelin and U46619-induced contractions with greater potency (three- to fivefold) against the former, while quercetin 3-glucoronide was inactive. Quercetin enhanced both the cyclic GMP content of the artery (threefold) and cyclic GMP-dependent relaxations to GTN and SNP (two to threefold), but forskolin-induced relaxations were unaffected. Although the effect of quercetin was qualitatively similar to that noted for UK-114,542, a selective inhibitor of phosphodiesterase 5, it was still evident against SNP-induced relaxations in the presence of 10 nM UK-114,542. Quercetin and quercetin 3'-sulphate significantly reduced the development of GTN-associated 'tolerance'.
  
  
  CONCLUSIONS
  Quercetin and quercetin 3'-sulphate inhibited receptor-mediated contractions of the porcine isolated coronary artery by an endothelium-independent action. Quercetin selectively enhanced cyclic-GMP-dependent relaxations by a mechanism not involving phosphodiesterase 5 inhibition. In addition, quercetin and quercetin 3'-sulphate opposed GTN-induced tolerance in vitro, which may be beneficial for patients treated for angina pectoris.
authors.affiliation: School of Biomedical Sciences, Faculty of Medical and Health Sciences, Queens Medical Centre, University of Nottingham, Nottingham, UK.
authors.forename: S
authors.initials: S
authors.lastname: Suri
authors.forename: X H
authors.initials: XH
authors.lastname: Liu
authors.forename: S
authors.initials: S
authors.lastname: Rayment
authors.forename: D A
authors.initials: DA
authors.lastname: Hughes
authors.forename: P A
authors.initials: PA
authors.lastname: Kroon
authors.forename: P W
authors.initials: PW
authors.lastname: Needs
authors.forename: M A
authors.initials: MA
authors.lastname: Taylor
authors.forename: S
authors.initials: S
authors.lastname: Tribolo
authors.forename: V G
authors.initials: VG
authors.lastname: Wilson
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism; D001158:Arteries / Q000187:drug effects / Q000378:metabolism; D001920:Bradykinin / Q000378:metabolism / Q000494:pharmacology; D003331:Coronary Vessels / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D006152:Cyclic GMP / Q000378:metabolism* / Q000494:pharmacology; D004361:Drug Tolerance; D009025:Morpholines; D005996:Nitroglycerin / Q000378:metabolism / Q000494:pharmacology*; D009599:Nitroprusside / Q000378:metabolism / Q000494:pharmacology; D011720:Pyrazoles; D011743:Pyrimidines; D011794:Quercetin / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D034421:Sus scrofa / Q000378:metabolism; D013552:Swine; D014662:Vasoconstrictor Agents / Q000378:metabolism / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000378:metabolism / Q000494:pharmacology*
chemical_list: C507274:5-(2-ethoxy-5(morpholinylacetyl)phenyl)-1,6-dihydro-1-methyl-3-propyl-7H-pyrazolo(4,3-d)pyrimidin-7-one methanesulphanate monohydrate; D009025:Morpholines; D011720:Pyrazoles; D011743:Pyrimidines; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; C531389:quercetin 3'-sulfate; D009599:Nitroprusside; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D011794:Quercetin; D005996:Nitroglycerin; D006152:Cyclic GMP; D001920:Bradykinin