title: Adenosine triggers preconditioning through MEK/ERK1/2 signalling pathway during hypoxia/reoxygenation in neonatal rat cardiomyocytes.
abstract: Three subtypes of adenosine receptors (A(1), A(2A) and A(3) ARs) are functionally expressed in cardiomyocytes. Adenosine released during ischemia and ischemia/reperfusion plays a major role in cardioprotection. Phosphatidylinositol 3-kinase (PI-3K)/protein kinase B (PKB) and MEK/ERK1/2 pathways are involved in cell survival. Since the role of these pathways in AR-mediated preconditioning is poorly understood, we have investigated whether PI-3K/PKB and/or MEK1/ERK1/2 pathways are involved in AR-induced cardioprotection in neonatal rat cardiomyocytes. Cells were pre-treated (15 min) with adenosine (non-selective), CPA (A(1)), CGS 21680 (A(2A)) or Cl-IB-MECA (A(3)) before 4 h hypoxia (0.5% O(2)) and 18 h reoxygenation (HX4/R). HX4/R-induced increase in LDH release was significantly reduced by adenosine (70%), CPA (59%) and Cl-IB-MECA (46%). The MEK1 inhibitor PD 98059 suppressed the effects of adenosine, CPA, and Cl-IB-MECA on LDH release, whereas the PI-3K inhibitor wortmannin did not reverse this cardioprotection. Western blotting of phosphorylated ERK1/2 and PKB during HX4/R supported the involvement of ERK1/2 and not PKB in A(1) and A(3) agonist-mediated cardioprotection. In addition, adenosine, CPA and Cl-IB-MECA inhibited HX4/R-induced caspase 3 activity by 75%, 70% and 59%, respectively, and this inhibition was abolished by PD 98059. Interestingly, wortmannin inhibited by 66% the anti-apoptotic response triggered by Cl-IB-MECA but had no effect on adenosine or CPA-induced inhibition of caspase 3. CGS 21680 did not modify cell survival or caspase 3 activity. In conclusion, these data show that the preconditioning effect of adenosine requires A(1) and A(3) but not A(2A) ARs and involves an anti-apoptotic effect via MEK1/ERK1/2 pathway in neonatal rat cardiomyocytes. In addition, A(3)AR-induced preconditioning also involves a PI-3K dependent pathway.
authors: Biomedical Research Centre, School of Biomedical and Natural Sciences, Nottingham-Trent-University, UK. renee.germack@ntu.ac.uk
authors: R
authors: R
authors: Germack
authors: J M
authors: JM
authors: Dickenson
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology*; D058907:Adenosine A1 Receptor Agonists; D058909:Adenosine A3 Receptor Agonists; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D053148:Caspase 3; D061945:Caspase Inhibitors; D015687:Cell Hypoxia; D002470:Cell Survival; D002478:Cells, Cultured; D005419:Flavonoids / Q000494:pharmacology; D019194:Ischemic Preconditioning; D007700:Kinetics; D048369:MAP Kinase Kinase 1 / Q000378:metabolism*; D048370:MAP Kinase Kinase 2 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D008954:Models, Biological; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D010627:Phenethylamines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D043682:Receptor, Adenosine A1 / Q000378:metabolism; D043705:Receptor, Adenosine A2A; D043684:Receptor, Adenosine A3 / Q000378:metabolism; D015398:Signal Transduction; D000077191:Wortmannin
chemical_list: D058907:Adenosine A1 Receptor Agonists; D058909:Adenosine A3 Receptor Agonists; D000730:Androstadienes; D061945:Caspase Inhibitors; D005419:Flavonoids; D010627:Phenethylamines; D047428:Protein Kinase Inhibitors; D043682:Receptor, Adenosine A1; D043705:Receptor, Adenosine A2A; D043684:Receptor, Adenosine A3; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; D019869:Phosphatidylinositol 3-Kinases; D048052:Mitogen-Activated Protein Kinase 3; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C505410:Casp3 protein, rat; D053148:Caspase 3; D000241:Adenosine; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000077191:Wortmannin