title: Multiple signalling pathways underlie the protective effect of levosimendan in cardiac myocytes.
abstract: Levosimendan is a cardiovascular drug for the treatment of acute and decompensated heart failure. The current weight of evidence on the cardioprotective effects of levosimendan originates from whole heart models and there is no information on the mechanism whereby signalling pathways are activated. In the present study, we investigated the effect of levosimendan on ischaemia/reperfusion injury and the underlying mechanism in cardiac myocytes. Pretreatment with levosimendan reversed the effects of ischaemia and ischaemia/reperfusion on cell viability and enhanced phosphorylation of Akt, p38-mitogen activated protein kinase (MAPK) and extracellular signal-regulated kinases 1/2 (ERK1/2). Inhibitors of these kinases and the blocker of the mitochondrial K(ATP) channels, 5-hydroxydecanoate, completely abolished the protection afforded by levosimendan. Levosimendan stimulated the phosphorylation of Akt, ERK1/2 and p38-MAPK with different kinetics and the activation of these pathways was dependent on the opening of the mitochondrial K(ATP) channels and the production of oxygen free radicals. The levosimendan-induced phosphorylation of ERK1/2 and Akt was reduced by inhibitors of epidermal growth factor receptor and Src. On the other hand, inhibition of the protein kinase A (PKA) pathway reduced phosphorylation of p38-MAPK. Furthermore, p38-MAPK was activated when a phosphodiesterase inhibitor or a selective PKA activator was used. Overall, our results suggest that levosimendan regulates the wiring of the natural salvaging pathways to execute the prosurvival signals. This network includes Akt, ERK1/2 and p38-MAPK. Opening of mitochondrial K(ATP) channels and the subsequent production of oxygen free radicals, the epidermal growth factor receptor/Src, and the cAMP/PKA pathways seem to mediate this response.
authors.affiliation: Laboratory of Animal Physiology, Department of Zoology, School of Biology, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.
authors.forename: Thomais
authors.initials: T
authors.lastname: Markou
authors.forename: Zoe
authors.initials: Z
authors.lastname: Makridou
authors.forename: Eleftheria
authors.initials: E
authors.lastname: Galatou
authors.forename: Antigone
authors.initials: A
authors.lastname: Lazou
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology*; D019610:Cytoprotection / Q000187:drug effects*; D006835:Hydrazones / Q000494:pharmacology*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010100:Oxygen / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D011724:Pyridazines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction / Q000187:drug effects*; D000077464:Simendan; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D002316:Cardiotonic Agents; D006835:Hydrazones; D047428:Protein Kinase Inhibitors; D011724:Pyridazines; D000077464:Simendan; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D010100:Oxygen