title: Apelin receptor (APJ) expression during cardiopulmonary bypass in children undergoing surgical repair.
abstract: OBJECTIVE
  In human adults, and animals, the Apelin-APJ ligand-receptor system is emerging as having a role in the pathogenesis of cardiovascular function and heart failure. The aim was to investigate expression, and regulation by oxygen, of the Apelin APJ receptor (APJ) in myocardium obtained from children undergoing corrective surgery with cardiopulmonary bypass for repair of congenital heart defects.
  
  
  METHODS
  Western blotting and Real-time PCR were used to determine if APJ was expressed in the infant myocardium, if expression was influenced by the duration of myocardial ischemia and if any relationship existed between APJ expression and early post-operative outcome. The next aim was to determine if there was a difference in mRNA expression of APJ in myocardium from cyanotic patients compared with acyanotic patients and if re-perfusing myocardium in vitro with either hypoxic, normoxic or hyperoxic oxygen affected APJ mRNA expression.
  
  
  RESULTS
  APJ was expressed in all myocardial samples and myocardium exposed to longer durations of ischemia and cardioplegia expressed higher levels of APJ (p<0.05). There was a significant correlation between APJ expression in myocardium resected after 10 min with both oxygen extraction ratio (p=0.021, rho= -0.523) and mixed venous oxygen saturation (p=0.028, rho 0.52). This association did not exist for myocardium collected before 10 min. There was no difference in APJ expression between cyanotic and acyanotic patients. No difference was found in APJ expression whether re-perfused with low, normal or high oxygen.
  
  
  CONCLUSIONS
  Changes in APJ expression were observed during cardiopulmonary bypass in children and the reasons for this require further investigation.
authors.affiliation: Institute of Medical Genetics, University of Glasgow School of Medicine, Royal Hospital for Sick Children, Glasgow, United Kingdom.
authors.forename: Susan
authors.initials: S
authors.lastname: Walker
authors.affiliation: Department of Paediatric Cardiac Surgery, Royal Hospital for Sick Children, Glasgow, United Kingdom.
authors.forename: Mark H D
authors.initials: MH
authors.lastname: Danton
authors.affiliation: Institute of Medical Genetics, University of Glasgow School of Medicine, Royal Hospital for Sick Children, Glasgow, United Kingdom.
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Lang
authors.affiliation: Institute of Medical Genetics, University of Glasgow School of Medicine, Royal Hospital for Sick Children, Glasgow, United Kingdom.
authors.forename: Fiona
authors.initials: F
authors.lastname: Lyall
mesh_terms: D000075244:Apelin Receptors; D002315:Cardiopulmonary Bypass; D002675:Child, Preschool; D003490:Cyanosis / Q000378:metabolism / Q000503:physiopathology; D005260:Female; D015870:Gene Expression; D006330:Heart Defects, Congenital / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D006801:Humans; D018496:Hyperoxia / Q000378:metabolism / Q000503:physiopathology; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology; D007223:Infant; D008297:Male; D017202:Myocardial Ischemia / Q000378:metabolism / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D010100:Oxygen / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*
chemical_list: C104575:APLNR protein, human; D000075244:Apelin Receptors; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D010100:Oxygen