title: Effects of blockade of the endothelin receptor A and inhibition of nitric oxide synthesis on uteroplacental and renal blood flow in awake pregnant rats.
abstract: OBJECTIVE
  The aim of this study was to evaluate the role of the ETA receptor and nitric oxide (NO) in the regulation of uteroplacental and renal blood flow in pregnant rats.
  
  
  METHODS
  Regional blood flows were measured by the microsphere technique in pregnant Sprague-Dawley rats (term 23 days). Blood flow was measured before and after ETA receptor blockade (BQ-123, 1 mg/kg) at gestational day (GD) 19 or 21 (n=8 and n=9, respectively). In 2 additional groups blood flow was measured before and after NO synthase inhibition (L-NAME 2 microg/min) at GD 19 or 21 (n=10 in each group).
  
  
  RESULTS
  BQ-123 significantly increased placental and myometrial blood flows by almost 80% and 35%, respectively, at both gestational ages. BQ-123 did not alter renal blood flow. No effect on placental or myometrial blood flow was observed after L-NAME infusion, neither at GD 19 nor GD 21. Renal blood flow decreased by nearly 35% in both groups after L-NAME.
  
  
  CONCLUSIONS
  There is an important role for endogenous ET in the regulation of uteroplacental blood flow in the rat. NO contributes to a significant vasodilatation in the renal vasculature; however, NO appears not to be involved in the maintenance of uteroplacental blood flow in the awake pregnant rat.
authors.affiliation: Department of Obstetrics and Gynecology, Karolinska University Hospital Huddinge, Karolinska Institute, Stockholm, Sweden. gunilla.ajne@kus.se
authors.forename: Gunilla
authors.initials: G
authors.lastname: Ajne
authors.forename: Henry
authors.initials: H
authors.lastname: Nisell
authors.forename: Thomas
authors.initials: T
authors.lastname: Jansson
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D065128:Endothelin Receptor Antagonists; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D007668:Kidney / Q000098:blood supply / Q000187:drug effects*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D010456:Peptides, Cyclic / Q000494:pharmacology*; D010920:Placenta / Q000098:blood supply / Q000187:drug effects*; D011247:Pregnancy; D011673:Pulsatile Flow; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow
chemical_list: D000959:Antihypertensive Agents; D065128:Endothelin Receptor Antagonists; D004791:Enzyme Inhibitors; D010456:Peptides, Cyclic; D019001:Nitric Oxide Synthase; C072247:cyclo(Trp-Asp-Pro-Val-Leu); D019331:NG-Nitroarginine Methyl Ester