title: Abnormal sinoatrial node development resulting from disturbed vascular endothelial growth factor signaling.
abstract: BACKGROUND
  Sinus node dysfunction is frequently observed in patients with congenital heart disease (CHD). Variants in the Vascular Endothelial Growth Factor-A (VEGF) pathway are associated with CHD. In Vegf(120/120) mice, over-expressing VEGF120, a reduced sinoatrial node (SAN) volume was suggested. Aim of the study is to assess the effect of VEGF over-expression on SAN development and function.
  
  
  METHODS
  Heart rate was measured in Vegf(120/120) and wildtype (WT) embryos during high frequency ultrasound studies at embryonic day (E)12.5, 14.5 and 17.5 and by optical mapping at E12.5. Morphology was studied with several antibodies. SAN volume estimations were performed, and qualitative-PCR was used to quantify expression of genes in SAN tissues of WT and Vegf(120/120) embryos.
  
  
  RESULTS
  Heart rate was reduced in Vegf(120/120) compared with WT embryos during embryonic echocardiography (52 ± 17 versus 125 ± 31 beats per minute (bpm) at E12.5, p<0.001; 123 ± 37 vs 160 ± 29 bmp at E14.5, p=0.024; and 177 ± 30 vs 217 ± 34 bmp, at E17.5 p=0.017) and optical mapping (81 ± 5 vs 116 ± 8 bpm at E12.5; p=0.003). The SAN of mutant embryos was smaller and more vascularized, and showed increased expression of the fast conducting gap junction protein, Connexin43.
  
  
  CONCLUSIONS
  Over-expression of VEGF120 results in reduced heart rate and a smaller, less compact and hypervascularized SAN with increased expression of Connexin43. This indicates that VEGF is necessary for normal SAN development and function.
authors.affiliation: Department of Paediatric Cardiology, Leiden University Medical Center, Leiden, The Netherlands; Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Emmeline E
authors.initials: EE
authors.lastname: Calkoen
authors.affiliation: Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Vicente-Steijn
authors.affiliation: Department of Paediatric Cardiology, Leiden University Medical Center, Leiden, The Netherlands; Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Nathan D
authors.initials: ND
authors.lastname: Hahurij
authors.affiliation: Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Conny J
authors.initials: CJ
authors.lastname: van Munsteren
authors.affiliation: Department of Paediatric Cardiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Arno A W
authors.initials: AA
authors.lastname: Roest
authors.affiliation: Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Marco C
authors.initials: MC
authors.lastname: DeRuiter
authors.affiliation: Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Steendijk
authors.affiliation: Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schalij
authors.affiliation: Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands; Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Adriana C
authors.initials: AC
authors.lastname: Gittenberger-de Groot
authors.affiliation: Department of Paediatric Cardiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Nico A
authors.initials: NA
authors.lastname: Blom
authors.affiliation: Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands; Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands. Electronic address: m.r.m.jongbloed@lumc.nl.
authors.forename: Monique R M
authors.initials: MR
authors.lastname: Jongbloed
mesh_terms: D000818:Animals; D001919:Bradycardia / Q000503:physiopathology; D018031:Connexin 43 / Q000378:metabolism; D004195:Disease Models, Animal; D004452:Echocardiography / Q000379:methods; D005260:Female; D006330:Heart Defects, Congenital / Q000235:genetics / Q000378:metabolism*; D006339:Heart Rate / Q000502:physiology; D051379:Mice; D038081:Organogenesis / Q000502:physiology; D016133:Polymerase Chain Reaction / Q000379:methods; D011247:Pregnancy; D012804:Sick Sinus Syndrome / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D012849:Sinoatrial Node / Q000002:abnormalities* / Q000196:embryology / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
chemical_list: D018031:Connexin 43; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse
keywords: Congenital heart disease; Heart development; Sick sinus syndrome; Sinoatrial node; Vascular endothelial growth factor