title: Effect of remote ischemic preconditioning on the melatonin and antioxidative status: a pilot study in patients undergoing cardiac surgery.
abstract: BACKGROUND
  Remote ischemic preconditioning (RIPC), a phenomenon in which a transient ischemia applied to a nonvital tissue protects another organ or tissue from subsequent lethal ischemic injury, is reported to protect the myocardium to withstand a subsequent prolonged ischemic event in patients undergoing cardiac surgery with cardiopulmonary bypass. It remains unclear whether oxidative stress and endogenous antioxidant enzymes play a role in the mechanistic pathways of RIPC. The aim of the present study was to evaluate the effects of RIPC on oxidative stress and extracellular concentrations of melatonin, extracellular superoxide dismutase (eSOD) and extracellular glutathione peroxidase (eGPx) in patients undergoing cardiac surgery with cardiopulmonary bypass.
  
  
  METHODS
  Thirty-two patients were randomly assigned to receive either RIPC (N.=15) or sham-RIPC (N.=17). Blood samples were collected immediately before and after RIPC and at the end of surgery. Melatonin levels were determined by radioimmunoassay. Plasma concentrations of eSOD, eGPx and 8-hydroxydeoxyguanosine (8-OhdG) as a marker of DNA oxidative stress were measured via ELISA.
  
  
  RESULTS
  We found that RIPC compared to Sham-RIPC independently predicted higher melatonin concentrations at the end of surgery. However, it had no effect on eSOD, eGPx, and DNA oxidative stress. eSOD levels significantly increased during CPB time, while systemic eGPx levels decreased. High baseline melatonin concentration independently predicted lower 8-OHdG levels at the end of surgery.
  
  
  CONCLUSIONS
  Our results suggest that extracellular antioxidative enzymes such as eSOD and eGPx as well as oxidative stress levels in the perioperative period do not play a predominant role in the mechanistic pathways of RIPC. RIPC modulates systemic melatonin concentrations but does not affect eSOD, eGPx and oxidative stress levels.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, Bonn, Germany.
authors.forename: Rafael
authors.initials: R
authors.lastname: Struck
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, Bonn, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Wittmann
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, Bonn, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Recht
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, Bonn, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Baumgarten
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Meybohm
authors.affiliation: Neonatology and Pediatric Intensive Care, Children's Hospital, University of Bonn, Bonn, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Müller
authors.affiliation: Neonatology and Pediatric Intensive Care, Children's Hospital, University of Bonn, Bonn, Germany - soyhan.bagci@ukb.uni-bonn.de.
authors.forename: Soyhan
authors.initials: S
authors.lastname: Bagci
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000368:Aged; D000975:Antioxidants / Q000378:metabolism*; D015415:Biomarkers / Q000097:blood; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D002315:Cardiopulmonary Bypass; D004249:DNA Damage; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000097:blood; D005260:Female; D005858:Germany; D005979:Glutathione Peroxidase / Q000097:blood; D006801:Humans; D019194:Ischemic Preconditioning / Q000009:adverse effects / Q000379:methods*; D008297:Male; D008550:Melatonin / Q000097:blood*; D008875:Middle Aged; D018384:Oxidative Stress; D010865:Pilot Projects; D012039:Regional Blood Flow; D013482:Superoxide Dismutase / Q000097:blood; D013997:Time Factors; D014111:Tourniquets; D016896:Treatment Outcome; D034941:Upper Extremity / Q000098:blood supply*
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D000080242:8-Hydroxy-2'-Deoxyguanosine; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D003849:Deoxyguanosine; D008550:Melatonin