title: Cardioprotective effect of δ-opioid receptor agonist vs. mild therapeutic hypothermia in a rat model of cardiac arrest with extracorporeal life support.
abstract: BACKGROUND
  To compare the effect of δ-opioid receptor agonist, d-Ala2-d-Leu5 enkephalin (DADLE) with normothermic control and therapeutic hypothermia on post resuscitation myocardial function in a model of extracorporeal life support (ECLS).
  
  
  METHODS
  Ventricular fibrillation (VF) was induced in male Wistar rats. After 10 min of untreated VF, venoarterial ECLS was instituted for 60 min. At the beginning of ECLS animals were randomized to three groups of ten: normothermia, hypothermia (32 °C) and DADLE intravenous infusion (1 mg/kg/h). Cooling to 32 °C or normothermia or drug infusion lasted for the entire ECLS. Plasma samples and myocardial biopsies were obtained and left-ventricular (LV) function was assessed by a conductance catheter at baseline and after weaning from ECLS.
  
  
  RESULTS
  DADLE administration resulted in a significantly enhanced recovery of LV systolic function expressed by slope of the LV end-systolic pressure volume relationship (Ees) and preload recruitable stroke work (PRSW) than hypothermia and normothermia. LV stiffness indicated by end-diastolic pressure volume relationship (EDPVR) was significantly lower after DADLE administration (P<0.01). LV relaxation described by Tau was preserved after DADLE treatment but not after normothermia or mild hypothermia (P<0.01). Plasma lactate concentrations were lower in DADLE group (P<0.05). DADLE and not conventional hypothermia significantly increased phosphorylation of the kinases ERK1 and 2 (3.9±0.3 and 3.1±0.5 vs. 0.4±0.1 and 0.3±0.1-fold of baseline levels) (P<0.001). Both DADLE and hypothermia but not normothermia increase phosphorylation of Akt.
  
  
  CONCLUSIONS
  DADLE was more effective than mild therapeutic hypothermia in recovering myocardial function and activation of the pro-survival kinases Akt and ERK after ECLS.
authors: Department of Surgery, Division of Cardiac Surgery, University of Verona, Verona, Italy. alessio.rungatscher@univr.it
authors: Alessio
authors: A
authors: Rungatscher
authors: Daniele
authors: D
authors: Linardi
authors: Alice
authors: A
authors: Giacomazzi
authors: Maddalena
authors: M
authors: Tessari
authors: Tiziano
authors: T
authors: Menon
authors: Alessandro
authors: A
authors: Mazzucco
authors: Giuseppe
authors: G
authors: Faggian
mesh_terms: D022561:Advanced Cardiac Life Support / Q000379:methods; D000818:Animals; D016308:Enkephalin, Leucine-2-Alanine / Q000627:therapeutic use*; D006323:Heart Arrest / Q000628:therapy*; D007036:Hypothermia, Induced / Q000379:methods; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D017465:Receptors, Opioid, delta / Q000819:agonists*
chemical_list: D017465:Receptors, Opioid, delta; D016308:Enkephalin, Leucine-2-Alanine