title: Increased myocardial methionine-enkephalin with reduced arterial oxygenation in congenital heart disease.
abstract: BACKGROUND
  Cardiac opioid peptides have been identified to exert important adaptive metabolic signalling for cardioprotection against ischaemia or hypoxia-related injury.
  
  
  OBJECTIVE
  To determine myocardial methionine-enkephalin content in children with hypoxemic congenital heart defects and to correlate myocardial content of methionine-enkephalin with the extent of arterial oxygen desaturation.
  
  
  METHODS
  Children (n= 20, median age of 16 months), undergoing cardiac surgical repair (tetralogy of Fallot, 17/20), were included in this study. Arterial oxygen saturation was measured on admission. Myocardial samples obtained during surgery were assayed via radioimmunochemistry for methionine-enkephalin content.
  
  
  RESULTS
  Greater methionine-enkephalin content was measured in the right ventricles of the patients suffering from recent cyanotic spells compared with those with no recent spells (cyanotic spells: 2418 ± 844 pg/g wet weight tissue, n= 6; no spells: 1175 ± 189 pg/g wet weight tissue, n= 14, P= 0.04). An inverse correlation was evident between the arterial oxygen saturation and myocardial methionine-enkephalin content.
  
  
  CONCLUSIONS
  Myocardial methionine-enkephalin levels increase with the severity of hypoxic stress in congenital cardiac disease and may play an important adaptive role in countering adrenergic over-activity and related excess demand on myocardial metabolic capacity.
authors.affiliation: Department of Cardiothoracic Surgery, Alfred Hospital, Department of Surgery, Monash University, Murdoch Children's Research Institute, Critical Care and Neurosciences, Heart Research, Victorian Paediatric Cardiac Surgery Unit, Department of Cardiology, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Olivier W V
authors.initials: OW
authors.lastname: van den Brink
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Cochrane
authors.forename: Franklin L
authors.initials: FL
authors.lastname: Rosenfeldt
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Penny
authors.forename: Salvatore
authors.initials: S
authors.lastname: Pepe
mesh_terms: D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D001784:Blood Gas Analysis; D006348:Cardiac Surgical Procedures / Q000379:methods* / Q000401:mortality; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004744:Enkephalin, Methionine / Q000032:analysis / Q000378:metabolism*; D005260:Female; D005500:Follow-Up Studies; D006330:Heart Defects, Congenital / Q000175:diagnosis / Q000401:mortality / Q000601:surgery*; D006801:Humans; D000860:Hypoxia / Q000151:congenital / Q000175:diagnosis*; D007223:Infant; D008297:Male; D009206:Myocardium / Q000378:metabolism; D010092:Oximetry; D010101:Oxygen Consumption / Q000502:physiology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D018570:Risk Assessment; D015996:Survival Rate; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D004744:Enkephalin, Methionine