title: Upregulation of genes involved in cardiac metabolism enhances myocardial resistance to ischemia/reperfusion in the rat heart.
abstract: Genes encoding enzymes involved in fatty acids (FA) and glucose oxidation are transcriptionally regulated by peroxisome proliferator-activated receptors (PPAR), members of the nuclear receptor superfamily. Under conditions associated with O(2) deficiency, PPAR-alpha modulates substrate switch (between FA and glucose) aimed at the adequate energy production to maintain basic cardiac function. Both, positive and negative effects of PPAR-alpha activation on myocardial ischemia/reperfusion (I/R) injury have been reported. Moreover, the role of PPAR-mediated metabolic shifts in cardioprotective mechanisms of preconditioning (PC) is relatively less investigated. We explored the effects of PPAR-alpha upregulation mimicking a delayed "second window" of PC on I/R injury in the rat heart and potential downstream mechanisms involved. Pretreatment of rats with PPAR-alpha agonist WY-14643 (WY, 1 mg/kg, i.p.) 24 h prior to I/R reduced post-ischemic stunning, arrhythmias and the extent of lethal injury (infarct size) and apoptosis (caspase-3 expression) in isolated hearts exposed to 30-min global ischemia and 2-h reperfusion. Protection was associated with remarkably increased expression of PPAR-alpha target genes promoting FA utilization (medium-chain acyl-CoA dehydrogenase, pyruvate dehydrogenase kinase-4 and carnitine palmitoyltransferase I) and reduced expression of glucose transporter GLUT-4 responsible for glucose transport and metabolism. In addition, enhanced Akt phosphorylation and protein levels of eNOS, in conjunction with blunting of cardioprotection by NOS inhibitor L-NAME, were observed in the WY-treated hearts.
  
  
  
  upregulation of PPAR-alpha target metabolic genes involved in FA oxidation may underlie a delayed phase PC-like protection in the rat heart. Potential non-genomic effects of PPAR-alpha-mediated cardioprotection may involve activation of prosurvival PI3K/Akt pathway and its downstream targets such as eNOS and subsequently reduced apoptosis.
authors: Institute for Heart Research, Slovak Academy of Sciences, Bratislava, Slovak Republic. usrdravi@savba.sk.
authors: T
authors: T
authors: Ravingerová
authors: S
authors: S
authors: Carnická
authors: V
authors: V
authors: Ledvényiová
authors: E
authors: E
authors: Barlaka
authors: E
authors: E
authors: Galatou
authors: A
authors: A
authors: Chytilová
authors: P
authors: P
authors: Mandíková
authors: M
authors: M
authors: Nemčeková
authors: A
authors: A
authors: Adameová
authors: F
authors: F
authors: Kolář
authors: A
authors: A
authors: Lazou
mesh_terms: D000818:Animals; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism*; D047493:PPAR alpha / Q000378:metabolism*; D011743:Pyrimidines / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D020127:Recovery of Function; D016896:Treatment Outcome; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D047493:PPAR alpha; D011743:Pyrimidines; C006253:pirinixic acid