title: Delta-opioid receptor activation mimics ischemic preconditioning in the canine heart.
abstract: The role of delta-opioid receptors in mediating ischemic preconditioning (IPC) in rats, rabbits, and pigs has been well-established; however, no studies have been performed in dogs. Therefore, the purpose of the present study was to determine if activation of delta-opioid receptors can mimic the cardioprotective effects of IPC in the canine heart and to determine if a nonselective opioid receptor antagonist could block IPC. All dogs were subjected to 60 minutes of left anterior descending (LAD) coronary artery occlusion and 3 hours of reperfusion. Ischemic preconditioning was produced by one 5-minute period of ischemia 10 minutes before LAD coronary artery occlusion. Infarct size (IS) expressed as a percent of the area at risk (AAR; IS/AAR) was determined by triphenyltetrazolium staining. Two selective delta-opioid receptor (DOR) agonists, TAN-67 and BW373U86, were administered by intracoronary infusion for 30 minutes before LAD occlusion and the opioid receptor antagonist naloxone was administered 30 minutes before IPC. Both TAN-67 and BW373U86 produced significant reductions in IS/AAR similar to that of IPC (control: 28+/-2.1; TAN: 12.3+/-2.2; IPC: 9.3+/-3.0: BW: 11.7+/-2.6). Naloxone attenuated the effect of IPC (control: 28+/-2.1; naloxone: 18.2+/-4.5). These results suggest that opioid receptors are important in IPC in dogs, and stimulation of delta-opioid receptors with selective agonists can mimic the cardioprotective effects of IPC and may have therapeutic potential.
authors.affiliation: Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53222, USA.
authors.forename: Jason N
authors.initials: JN
authors.lastname: Peart
authors.forename: Hemal H
authors.initials: HH
authors.lastname: Patel
authors.forename: Garrett J
authors.initials: GJ
authors.lastname: Gross
mesh_terms: D000818:Animals; D001549:Benzamides / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D004195:Disease Models, Animal; D004285:Dogs; D007261:Infusions, Intra-Arterial; D019157:Ischemic Preconditioning, Myocardial; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D011804:Quinolines / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D017465:Receptors, Opioid, delta / Q000819:agonists* / Q000502:physiology
chemical_list: D001549:Benzamides; D010879:Piperazines; D011804:Quinolines; D017465:Receptors, Opioid, delta; C094142:TAN 67; C083877:BW 373U86