title: Inconsistent relation of MAPK activation to infarct size reduction by ischemic preconditioning in pigs.
abstract: The importance of the activation of mitogen-activated protein kinases (MAPK) for the cardioprotection achieved by ischemic preconditioning (IP) is still controversial. We therefore measured infarct size and p38, extracellular signal-regulated kinase (ERK), and c-Jun NH(2)-terminal kinase (JNK) MAPK phosphorylation (by biopsies) in enflurane-anesthetized pigs. After 90 min low-flow ischemia and 120 min reperfusion, infarct size averaged 18.3 +/- 12.4 (SD)% (group 1, n = 14). At similar subendocardial blood flows, IP by 10 min ischemia and 15 min reperfusion (group 2, n = 14) reduced infarct size to 6.2 +/- 5.1% (P < 0.05). An inconsistent increase in p38, ERK, and p54 JNK phosphorylation (by Western blot) was found during IP; p46 JNK phosphorylation increased with the subsequent reperfusion. At 8 min of the sustained ischemia, p38, ERK, and p54 JNK phosphorylation were increased with no difference between groups (medians: p38: 207% of baseline in group 1 vs. 153% in group 2; ERK: 142 vs. 144%; p54 JNK: 171 vs. 155%, respectively). MAPK phosphorylation and reduction of infarct size by IP were not correlated, thus not supporting the concept of a causal role of MAPK in mediating cardioprotection by IP.
authors.affiliation: Abteilung für Pathophysiologie, Zentrum für Innere Medizin des Universitätsklinikums Essen, 45122 Essen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Behrends
authors.forename: R
authors.initials: R
authors.lastname: Schulz
authors.forename: H
authors.initials: H
authors.lastname: Post
authors.forename: A
authors.initials: A
authors.lastname: Alexandrov
authors.forename: S
authors.initials: S
authors.lastname: Belosjorow
authors.forename: M C
authors.initials: MC
authors.lastname: Michel
authors.forename: G
authors.initials: G
authors.lastname: Heusch
mesh_terms: D000818:Animals; D003326:Coronary Circulation; D004195:Disease Models, Animal; D005260:Female; D006439:Hemodynamics; D019157:Ischemic Preconditioning, Myocardial; D048031:JNK Mitogen-Activated Protein Kinases; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009203:Myocardial Infarction / Q000378:metabolism* / Q000473:pathology; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation; D013556:Swine, Miniature; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases