title: Phosphatidylinositol 3-kinase and ERK1/2 are not involved in adenosine A1, A2A or A3 receptor-mediated preconditioning in rat ventricle strips.
abstract: Mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase 1 and 2 (ERK1/2) and phosphatidylinositol 3-kinase (PI3-kinase)/protein kinase B (PKB; also known as Akt) are important antiapoptotic signalling pathways which have recently been implicated in cardioprotection. However, at present the involvement of ERK1/2 and PI3-kinase/PKB in adenosine receptor-mediated cardioprotection is poorly understood. In this study we used isolated rat right ventricular strips, contracted by electrical-field stimulation, in order to investigate the role of ERK1/2 and PI3-kinase/PKB in adenosine receptor-induced cardioprotection. Ventricle strips were pretreated for 2 min with the agonists adenosine (non-selective), CPA (A1 selective), CGS 21680 (A2A selective) and Cl-IB-MECA (A3 selective) before 30 min hypoxia followed by 30 min reoxygenation. Each agonist significantly improved posthypoxic percentage contraction recovery compared to control strips. Similarly hypoxic preconditioning (10 min hypoxia followed by 20 min reoxygenation) significantly improved posthypoxic percentage contraction recovery compared to non-preconditioned strips. The selective adenosine receptor antagonists DPCPX (A1), ZM 241385 (A2A) and MRS 1220 (A3) attenuated cardioprotection induced by CPA, CGS 21680 and Cl-IB-MECA, respectively. Pre-incubation (30 min) of ventricle strips with the MEK1 inhibitor PD 98059 (50 microM) or the PI3-kinase inhibitor wortmannin (100 nM) significantly reduced posthypoxic percentage contraction recovery induced by hypoxic preconditioning. In contrast, PD 98059 and wortmannin had no significant effect on cardioprotection induced by CPA, Cl-IB-MECA or CGS 21680. Overall these data indicate that although selective A1, A2A and A3 adenosine receptor agonists induce preconditioning in rat right ventricular strips the effects are independent of ERK1/2- and PI3-kinase-dependent pathways. In contrast ERK1/2 and PI3-kinase-dependent pathways do appear to be involved in early hypoxic preconditioning.
authors.affiliation: School of Biomedical and Natural Sciences, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK.
authors.forename: Laura
authors.initials: L
authors.lastname: Button
authors.forename: Stewart E
authors.initials: SE
authors.lastname: Mireylees
authors.forename: Renee
authors.initials: R
authors.lastname: Germack
authors.forename: John M
authors.initials: JM
authors.lastname: Dickenson
mesh_terms: D058907:Adenosine A1 Receptor Agonists; D058916:Adenosine A1 Receptor Antagonists; D058908:Adenosine A2 Receptor Agonists; D058917:Adenosine A2 Receptor Antagonists; D058909:Adenosine A3 Receptor Agonists; D058918:Adenosine A3 Receptor Antagonists; D000818:Animals; D004558:Electric Stimulation; D006352:Heart Ventricles / Q000187:drug effects; D066298:In Vitro Techniques; D019157:Ischemic Preconditioning, Myocardial; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology*; D048052:Mitogen-Activated Protein Kinase 3 / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017208:Rats, Wistar; D043682:Receptor, Adenosine A1 / Q000502:physiology*; D043705:Receptor, Adenosine A2A / Q000502:physiology*; D043684:Receptor, Adenosine A3 / Q000502:physiology*; D016276:Ventricular Function
chemical_list: D058907:Adenosine A1 Receptor Agonists; D058916:Adenosine A1 Receptor Antagonists; D058908:Adenosine A2 Receptor Agonists; D058917:Adenosine A2 Receptor Antagonists; D058909:Adenosine A3 Receptor Agonists; D058918:Adenosine A3 Receptor Antagonists; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D043682:Receptor, Adenosine A1; D043705:Receptor, Adenosine A2A; D043684:Receptor, Adenosine A3; C494920:Akt1 protein, rat