title: Adenosine A(3) receptor activation protects the myocardium from reperfusion/reoxygenation injury.
abstract: Ischemia-reperfusion induces both necrotic and apoptotic cell death. The ability of adenosine to attenuate reperfusion-induced injury (RI) and the role played by adenosine receptors are unclear. We therefore studied the role of the A(3) receptor (A(3)R) in ameliorating RI using the specific A(3)R agonist 1-[2-chloro-6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-1-deoxi-N-methyl-b-D-ribofuranuronamide (2-Cl-IB-MECA). Isolated rat hearts and cardiomyocytes were subjected to ischemia or simulated ischemia, followed by reperfusion/reoxygenation. The end points were percent infarction/risk zone and annexin-V (apoptosis) and/or propidium iodide positivity (necrosis), respectively. In isolated hearts, 2-Cl-IB-MECA significantly limited infarct size (44.2 +/- 2.7% in control vs. 21.9 +/- 2.4% at 1 nM and 35.8 +/- 3.3% at 0.1 nM, P < 0.05). In isolated myocytes, apoptosis and necrosis were significantly reduced compared with controls (5.7 +/- 2.6% vs. 17.1 +/- 1.3% and 13.7 +/- 2.0% vs. 23.1 +/- 1.5%, respectively, P < 0.0001). In both models, the beneficial effects were abrogated using the A(3)R antagonist MRS-1191. The involvement of A(2a) receptor activation was also examined. This is the first study to demonstrate that A(3)R activation at reperfusion limits myocardial injury in the isolated rat heart and improves survival in isolated myocytes, possibly by antiapoptotic and antinecrotic mechanisms.
authors.affiliation: The Hatter Institute for Cardiovascular Studies, Division of Cardiology, University College London Hospitals and Medical School, United Kingdom.
authors.forename: Helen L
authors.initials: HL
authors.lastname: Maddock
authors.forename: Mihaela M
authors.initials: MM
authors.lastname: Mocanu
authors.forename: Derek M
authors.initials: DM
authors.lastname: Yellon
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002316:Cardiotonic Agents / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D009203:Myocardial Infarction / Q000378:metabolism / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000473:pathology; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D009336:Necrosis; D010100:Oxygen / Q000494:pharmacology; D058906:Purinergic P1 Receptor Agonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D043684:Receptor, Adenosine A3; D018047:Receptors, Purinergic P1 / Q000378:metabolism*
chemical_list: D002316:Cardiotonic Agents; D058906:Purinergic P1 Receptor Agonists; D043684:Receptor, Adenosine A3; D018047:Receptors, Purinergic P1; D000241:Adenosine; D010100:Oxygen; C090034:2-chloro-N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide