title: Role of the AT2 receptor in modulating the angiotensin II contractile response of the uterine artery at mid-gestation.
abstract: BACKGROUND
  During human pregnancy, circulating concentrations of components of the renin-angiotensin system increase, but pressor refractoriness to angiotensin II (Ang-II) is observed. Given the importance of the Ang-II pressor response in deciding susceptibility to preeclampsia and of the Ang-II system for controlling uterine vasoreactivity, we sought to address the effects of pregnancy on the reactivity of the isolated uterine artery (UA) in mice.
  
  
  METHODS
  Blood pressure was measured throughout pregnancy in awake C57BL/6J mice. UA segments were isolated from three groups of animals (non-pregnant, mid [day 12-13] and late [day 18-19] gestation) and studied by wire myography.
  
  
  RESULTS
  UA diameters, KCl-mediated responses, and acetylcholine-dependent vasorelaxation were greater at mid and late gestation than in non-pregnant animals. Ang-II responses were also greater during pregnancy, with an increased contraction in response to AT2 receptor blockade at mid-gestation. AT1 receptor blockade abolished the Ang-II response in all groups.
  
  
  CONCLUSIONS
  Study findings are consistent with the possibility that AT2 receptor-mediated vasodilatation plays a role in modulating Ang-II contractile responses in pregnancy.
authors.affiliation: Department of Obstetrics and Gynecology, Wake Forest University, Winston-Salem, NC 27157, USA. vpulgar@wfubmc.edu
authors.forename: Victor M
authors.initials: VM
authors.lastname: Pulgar
authors.forename: Henry
authors.initials: H
authors.lastname: Yamashiro
authors.forename: James C
authors.initials: JC
authors.lastname: Rose
authors.forename: Lorna G
authors.initials: LG
authors.lastname: Moore
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000109:Acetylcholine / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011189:Potassium Chloride / Q000494:pharmacology; D011247:Pregnancy; D044139:Receptor, Angiotensin, Type 2 / Q000378:metabolism*; D055988:Uterine Artery / Q000187:drug effects* / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects
chemical_list: D044139:Receptor, Angiotensin, Type 2; D000804:Angiotensin II; D011189:Potassium Chloride; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000109:Acetylcholine