title: The ecto-nucleotidase NTPDase1 differentially regulates P2Y1 and P2Y2 receptor-dependent vasorelaxation.
abstract: OBJECTIVE
  Extracellular nucleotides produce vasodilatation through endothelial P2 receptor activation. As these autacoids are actively metabolized by the ecto-nucleotidase nucleoside triphosphate diphosphohydrolase-1 (NTPDase1), we studied the effects of this cell surface enzyme on nucleotide-dependent vasodilatation.
  
  
  METHODS
  Vascular NTPDase expression and activity were evaluated by immunohistochemistry and histochemistry. The vascular effects of nucleotides were tested in vivo by monitoring mean arterial pressure, and in vitro comparing reactivity of aortic rings using wild-type and Entpd1(-/-) (lacking NTPDase1) mice.
  
  
  RESULTS
  The absence of NTPDase1 in Entpd1(-/-) mice led to a dramatic drop in endothelial nucleotidase activity. This deficit was associated with an exacerbated decrease in blood pressure after nucleotide injection. Following ATP injection, mean arterial pressure was decreased in Entpd1(+/+) and Entpd1(-/-) mice by 5.0 and 17%, respectively, and by 0.1 and 19% after UTP injection (10 nmole.kg(-1) both). In vitro, the concentration-response curves of relaxation to ADP and ATP were shifted to the left, revealing a facilitation of endothelial P2Y1 and P2Y2 receptor activation in Entpd1(-/-) mice. EC(50) values in Entpd1(+/+) versus Entpd1(-/-) aortic rings were 14 microM versus 0.35 microM for ADP, and 29 microM versus 1 microM for ATP. In Entpd1(-/-) aortas, P2Y1 receptors were more extensively desensitized than P2Y2 receptors. Relaxations to the non-hydrolysable analogues ADPbetaS (P2Y1) and ATPgammaS (P2Y2) were equivalent in both genotypes confirming the normal functionality of these P2Y receptors in mutant mice.
  
  
  CONCLUSIONS
  NTPDase1 controls endothelial P2Y receptor-dependent relaxation, regulating both agonist level and P2 receptor reactivity.
authors.affiliation: Centre de Recherche en Rhumatologie et Immunologie, Centre Hospitalier Universitaire de Québec, Université Laval, Québec, QC, Canada.
authors.forename: Gilles
authors.initials: G
authors.lastname: Kauffenstein
authors.forename: Cristina Ribas
authors.initials: CR
authors.lastname: Fürstenau
authors.forename: Pedro
authors.initials: P
authors.lastname: D'Orléans-Juste
authors.forename: Jean
authors.initials: J
authors.lastname: Sévigny
mesh_terms: D000244:Adenosine Diphosphate / Q000031:analogs & derivatives; D000251:Adenosine Triphosphatases; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives; D000818:Animals; D001011:Aorta / Q000378:metabolism / Q000502:physiology; D003433:Crosses, Genetic; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009705:Nucleosides / Q000494:pharmacology; D009708:Nucleotidases / Q000494:pharmacology; D009711:Nucleotides / Q000494:pharmacology*; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D058472:Receptors, Purinergic P2Y1; D058473:Receptors, Purinergic P2Y2; D013873:Thionucleotides; D014544:Uridine Triphosphate / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D009705:Nucleosides; D009711:Nucleotides; C546383:P2ry1 protein, mouse; C546386:P2ry2 protein, mouse; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D058473:Receptors, Purinergic P2Y2; D013873:Thionucleotides; C030812:adenosine 5'-O-(2-thiodiphosphate); C022571:adenosine 5'-O-(3-thiotriphosphate); D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D009708:Nucleotidases; C030287:nucleotidase; D000251:Adenosine Triphosphatases; C027201:ectoATPase; D014544:Uridine Triphosphate