title: The role of differential activation of p38-mitogen-activated protein kinase in preconditioned ventricular myocytes.
abstract: Activation of protein kinase C (PKC) and more recently mitogen-activated protein kinases (MAPKs) have been associated with the cardioprotective effect of ischemic preconditioning. We examined the interplay between these kinases in a characterized model of ischemic preconditioning in cultured rat neonatal ventricular cardiocytes where ectopic expression of active PKC-delta results in protection. Two members of the MAPK family, p38 and p42/44, were activated transiently during preconditioning by brief simulated ischemia/reoxygenation. Overexpression of active PKC-delta, rather than augmenting, completely abolished this activation. We therefore determined whether a similar process occurred during lethal prolonged simulated ischemia. In contrast to ischemia, brief, lethal-simulated ischemia activated only p38 (2.8+/-0.45 vs. basal, P<0.01), which was attenuated by expression of active PKC-delta or by preconditioning (0.48+/-0.1 vs. ischemia, P<0.01). To determine whether reduced p38 activation was the cause or an effect of protection, we used SB203580, a p38 inhibitor. SB203580 reduced ischemic injury (CK release 38.0+/-3.1%, LDH release 77.3+/-4.0%, and MTT bioreduction 127.1+/-4.8% of control, n=20, P<0.05). To determine whether p38 activation was isoform selective, myocytes were infected with adenoviruses encoding wild-type p38alpha or p38beta. Transfected p38alpha and beta show differential activation (P<0.001) during sustained simulated ischemia, with p38alpha remaining activated (1.48+/-0.36 vs. basal) but p38beta deactivated (0.36+/-0.1 vs. basal, P<0.01). Prior preconditioning prevented the activation of p38alpha (0.65+/-0.11 vs. ischemia, P<0.05). Moreover, cells expressing a dominant negative p38alpha, which prevented ischemic p38 activation, were resistant to lethal simulated ischemia (CK release 82.9+/-3.9% and MTT bioreduction 130.2+/-6.5% of control, n=8, P<0.05). Thus, inhibition of p38alpha activation during ischemia reduces injury and may contribute to preconditioning-induced cardioprotection in this model.
authors.affiliation: Department of Cardiology, KCL, The Rayne Institute, St. Thomas' Hospital London SE1 7EH, U.K.
authors.forename: A T
authors.initials: AT
authors.lastname: Saurin
authors.forename: J L
authors.initials: JL
authors.lastname: Martin
authors.forename: R J
authors.initials: RJ
authors.lastname: Heads
authors.forename: C
authors.initials: C
authors.lastname: Foley
authors.forename: J W
authors.initials: JW
authors.lastname: Mockridge
authors.forename: M J
authors.initials: MJ
authors.lastname: Wright
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: M S
authors.initials: MS
authors.lastname: Marber
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006352:Heart Ventricles / Q000166:cytology / Q000201:enzymology*; D000860:Hypoxia; D007093:Imidazoles / Q000494:pharmacology; D019194:Ischemic Preconditioning; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism; D051745:Protein Kinase C-delta; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D004791:Enzyme Inhibitors; D007093:Imidazoles; D007527:Isoenzymes; D011725:Pyridines; C497260:Prkcd protein, rat; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580