title: Adaptation to pregnancy leads to attenuated rat uterine artery smooth muscle sensitivity to oxytocin.
abstract: OBJECTIVE
  We tested the hypothesis that oxytocin (OT) contracts blood vessels via vasopressin V1A (VP) receptors, and that this depends on pregnancy.
  
  
  METHODS
  Concentration-contraction relationships (CCR) to OT and VP (10(-12)-10(-6) mol/L) were obtained in different blood vessels. CCR were obtained in uterine arteries (UA) from nonpregnant, mid-pregnant, and late pregnant rats (n = 6-10 per group) in the absence and presence of selective antagonists (10(-7) mol/L).
  
  
  RESULTS
  Sensitivity to OT, but not to VP, is attenuated in pregnant rat UA. Antagonists shifted CCR of OT and VP to the right, and, to a lesser extent, of the counterpart, in all UA. VP antagonist depresses oxytocin CCR much more than OT antagonist in pregnant rat UA.
  
  
  CONCLUSIONS
  OT and VP contract UA via their own receptors, although partial cross-activation is evident. Adaptation to pregnancy led to attenuated sensitivity of UA smooth muscle to OT and transformed OT receptors into VP-like ones.
authors.affiliation: Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: Yuri P
authors.initials: YP
authors.lastname: Vedernikov
authors.forename: Ancizar
authors.initials: A
authors.lastname: Betancourt
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Wentz
authors.forename: George R
authors.initials: GR
authors.lastname: Saade
authors.forename: Robert E
authors.initials: RE
authors.lastname: Garfield
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001013:Aorta, Thoracic / Q000187:drug effects; D001127:Arginine Vasopressin / Q000031:analogs & derivatives / Q000494:pharmacology; D001158:Arteries / Q000187:drug effects / Q000378:metabolism; D003199:Computer Systems; D004305:Dose-Response Relationship, Drug; D005260:Female; D005263:Femoral Artery / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009994:Osmolar Concentration; D010120:Oxytocics / Q000008:administration & dosage / Q000494:pharmacology*; D010121:Oxytocin / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology*; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018045:Receptors, Oxytocin / Q000037:antagonists & inhibitors / Q000235:genetics; D017483:Receptors, Vasopressin / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014599:Uterus / Q000098:blood supply*; D014661:Vasoconstriction; D014667:Vasopressins / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology
chemical_list: D065092:Antidiuretic Hormone Receptor Antagonists; D010120:Oxytocics; D012333:RNA, Messenger; D018045:Receptors, Oxytocin; D017483:Receptors, Vasopressin; C509322:oxytocin, d(CH2)5(1)-Tyr(OMe)(2)-Orn(8)-; C509323:vasopressin, d(CH2)5(1)-Tyr(OMe)(2)-Arg(8)-; D014667:Vasopressins; D001127:Arginine Vasopressin; D010121:Oxytocin