title: Contribution of different local vascular responses to mid-gestational vasodilation.
abstract: OBJECTIVE
  At-term pregnancy-induced vasodilation is the resultant of endothelium-dependent vasodilation, decreased myogenic reactivity, increased compliance, and reduced sensitivity to vasoconstrictor agents. We hypothesized that these vascular changes are already present at mid-gestation.
  
  
  METHODS
  In 20 mid-pregnant and 20 nonpregnant Wistar Hannover rats, we measured vascular responses of isolated mesenteric arteries and kidney.
  
  
  RESULTS
  In the pregnant rats compared with the nonpregnant rats, mesenteric flow-mediated vasodilation and renal perfusion flow increased 1.52-fold (from 47±5 to 31±4 μL/min) and 1.13-fold (from 12.8±0.1 to 14.4±0.1 mL/min), respectively. Nitric oxide inhibition reduced mesenteric flow-mediated vasodilation to a similar extent in the pregnant and nonpregnant rats; it completely blocked the pregnancy-induced increase in renal perfusion flow. Pregnancy did not change mesenteric artery sensitivity to phenylephrine, myogenic reactivity, nor vascular compliance.
  
  
  CONCLUSIONS
  At mid-gestation, alterations in rat mesenteric vascular tone depend primarily on flow-mediated endothelium-dependent changes and not on changes in α-adrenergic vasoconstrictor sensitivity, myogenic reactivity, or vascular compliance.
authors.affiliation: Department of Obstetrics and Gynecology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. j.vandrongelen@obgyn.umcn.nl
authors.forename: Joris
authors.initials: J
authors.lastname: van Drongelen
authors.forename: Jeanne
authors.initials: J
authors.lastname: Pertijs
authors.forename: Alfons
authors.initials: A
authors.lastname: Wouterse
authors.forename: Rob
authors.initials: R
authors.lastname: Hermsen
authors.forename: Fred C G J
authors.initials: FC
authors.lastname: Sweep
authors.forename: Frederik K
authors.initials: FK
authors.lastname: Lotgering
authors.forename: Paul
authors.initials: P
authors.lastname: Smits
authors.forename: Marc E A
authors.initials: ME
authors.lastname: Spaanderman
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005865:Gestational Age; D006801:Humans; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D010656:Phenylephrine / Q000494:pharmacology*; D011247:Pregnancy; D011270:Pregnancy, Animal; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D012077:Renal Artery / Q000187:drug effects / Q000502:physiology; D012680:Sensitivity and Specificity; D013152:Splanchnic Circulation / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
chemical_list: D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D019331:NG-Nitroarginine Methyl Ester