title: Coronary flow reserve in pregnant rats with increased left ventricular afterload.
abstract: BACKGROUND
  Coronary flow reserve (CFR) is used as a measure of coronary endothelial function. We investigated the effect of increased afterload on CFR of pregnant and non-pregnant rats.
  
  
  METHODS
  Afterload increase in Wister rats (both pregnant and non-pregnant) was achieved by the infusion of angiotensin II (Ang II) for ∼10 days or by subjecting them to transverse aortic constriction (TAC) for ∼14 days. Control groups were infused with 0.9% NaCl or had sham surgery, respectively. In pregnant rats, the experiments were performed close to term gestation. Doppler velocity waveforms of the left main coronary artery were recorded using a high resolution ultrasound imaging system (Vevo 770, VisualSonics, Canada) at baseline while the animals were anesthetized with 1.5% inhaled isoflurane, and during maximal coronary dilatation obtained by the inhalation of 3.5% of isoflurane. CFR was calculated as the ratio between the peak coronary flow velocities (CFRpeak) and the velocity-time integrals (CFRVTI) recorded at hyperemia and at baseline.
  
  
  RESULTS
  CFR could be calculated in 60 of 75 (80%) animals. There were no differences in CFR between intervention and control groups irrespective of whether afterload was increased by Ang II or TAC. In the TAC-study CFRpeak (1.54±0.07 vs 1.85±0.17; p = 0.03) was decreased in pregnant compared to non-pregnant shams. When sham animals from both studies were pooled together both CFRpeak (1.42±0.07 vs 1.86±0.16; p = 0.005) as well as CFRVTI (1.45±0.07 vs 1.78±0.12; p = 0.03) were significantly lower in pregnant rats compared to non-pregnant.
  
  
  CONCLUSIONS
  CFR can be measured non-invasively in rats using Doppler echocardiography and high concentrations of inhaled isoflurane as a coronary vasodilator. In pregnant rats, CFR is reduced close to term. CFR is not affected by increased left ventricular afterload caused by chronic Ang II infusion or TAC.
authors.affiliation: Women's Health and Perinatology Research Group, Institute of Clinical Medicine, Faculty of Health Sciences, UiT - The Arctic University of Norway, Tromsø, Norway; Department of Pediatrics, University Hospital of Northern Norway, Tromsø, Norway.
authors.forename: Nils Thomas
authors.initials: NT
authors.lastname: Songstad
authors.affiliation: Division of Pediatric Cardiology, Department of Pediatrics, University of Miami, Jackson Memorial Hospital, Miami, Florida, United States of America.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Serrano
authors.affiliation: Women's Health and Perinatology Research Group, Institute of Clinical Medicine, Faculty of Health Sciences, UiT - The Arctic University of Norway, Tromsø, Norway; Department of Obstetrics and Gynecology, University Hospital of Northern Norway, Tromsø, Norway.
authors.forename: Vasilis
authors.initials: V
authors.lastname: Sitras
authors.forename: David
authors.initials: D
authors.lastname: Johansen
authors.affiliation: Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Science, UiT - The Arctic University of Norway, Tromsø, Norway.
authors.forename: Davis
authors.initials: D
authors.lastname: Johansen
authors.affiliation: Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Science, UiT - The Arctic University of Norway, Tromsø, Norway.
authors.forename: Kirsti
authors.initials: K
authors.lastname: Ytrehus
authors.affiliation: Women's Health and Perinatology Research Group, Institute of Clinical Medicine, Faculty of Health Sciences, UiT - The Arctic University of Norway, Tromsø, Norway; Department of Obstetrics and Gynecology, University Hospital of Northern Norway, Tromsø, Norway.
authors.forename: Ganesh
authors.initials: G
authors.lastname: Acharya
mesh_terms: D000804:Angiotensin II / Q000008:administration & dosage; D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology*; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology*; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D014662:Vasoconstrictor Agents / Q000008:administration & dosage; D016277:Ventricular Function, Left / Q000187:drug effects
chemical_list: D014662:Vasoconstrictor Agents; D000804:Angiotensin II