title: Role of soluble epoxide hydrolase in postischemic recovery of heart contractile function.
abstract: Cytochrome P450 epoxygenases metabolize arachidonic acid to epoxyeicosatrienoic acids (EETs) which are converted to dihydroxyeicosatrienoic acids (DHETs) by soluble epoxide hydrolase (Ephx2, sEH). To examine the functional role of sEH in the heart, mice with targeted disruption of the Ephx2 gene were studied. Hearts from sEH null mice have undetectable levels of sEH mRNA and protein and cannot convert EETs to DHETs. sEH null mice have normal heart anatomy and basal contractile function, but have higher fatty acid epoxide:diol ratios in plasma and cardiomyocyte cell culture media compared with wild type (WT). sEH null hearts have improved recovery of left ventricular developed pressure (LVDP) and less infarction compared with WT hearts after 20 minutes ischemia. Perfusion with the putative EET receptor antagonist 14,15-epoxyeicosa-5(Z)-enoic acid (10 to 100 nmol/L) before ischemia abolishes this cardioprotective phenotype. Inhibitor studies demonstrate that perfusion with phosphatidylinositol-3 kinase (PI3K) inhibitors wortmannin (200 nmol/L) or LY294002 (5 micromol/L), the ATP-sensitive K+ channel (K(ATP)) inhibitor glibenclamide (1 micromol/L), the mitochondrial K(ATP) (mitoK(ATP)) inhibitor 5-hydroxydecanoate (100 to 200 micromol/L), or the Ca2+-sensitive K+ channel (K(Ca)) inhibitor paxilline (10 micromol/L) abolishes the cardioprotection in sEH null hearts. Consistent with increased activation of the PI3K cascade, sEH null mice exhibit increased cardiac expression of glycogen synthase kinase-3beta (GSK-3beta) phospho-protein after ischemia. Together, these data suggest that targeted disruption of sEH increases the availability of cardioprotective EETs that work by activating PI3K signaling pathways and K+ channels.
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada.
authors.forename: John M
authors.initials: JM
authors.lastname: Seubert
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Sinal
authors.forename: Joan
authors.initials: J
authors.lastname: Graves
authors.forename: Laura M
authors.initials: LM
authors.lastname: DeGraff
authors.forename: J Alyce
authors.initials: JA
authors.lastname: Bradbury
authors.forename: Craig R
authors.initials: CR
authors.lastname: Lee
authors.forename: Kerry
authors.initials: K
authors.lastname: Goralski
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Carey
authors.forename: Ayala
authors.initials: A
authors.lastname: Luria
authors.forename: John W
authors.initials: JW
authors.lastname: Newman
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Hammock
authors.forename: John R
authors.initials: JR
authors.lastname: Falck
authors.forename: Holly
authors.initials: H
authors.lastname: Roberts
authors.forename: Howard A
authors.initials: HA
authors.lastname: Rockman
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Murphy
authors.forename: Darryl C
authors.initials: DC
authors.lastname: Zeldin
mesh_terms: D000818:Animals; D017548:Echocardiography, Transesophageal; D004851:Epoxide Hydrolases / Q000378:metabolism*; D005905:Glyburide / Q000494:pharmacology; D006321:Heart / Q000503:physiopathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008929:Mitochondria, Heart / Q000187:drug effects / Q000201:enzymology; D009200:Myocardial Contraction / Q000502:physiology*; D017202:Myocardial Ischemia / Q000201:enzymology* / Q000503:physiopathology; D009206:Myocardium / Q000201:enzymology
chemical_list: D004851:Epoxide Hydrolases; D005905:Glyburide