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Soluble epoxide hydrolase (sEH) metabolizes epoxyeicosatrienoic acids (EETs), primarily 14,15-EET. EETs are derived from arachidonic acid via P-450 epoxygenases and are cardioprotective. We tested the hypothesis that sEH deficiency and pharmacological inhibition elicit tolerance to ischeniia via EETmediated STAT3 signaling in vitro and in vivo. In addition, the relevance of single nucleotide polymorphisms (SNPs) of EPHX2 (the gene encoding sEH) on tolerance to oxygen and glucose deprivation and reoxygenation and glucose repletion (OGD/RGR) was assessed in male C57BL\6J (WT) or sEH knockout (sEHKO) cardiomyocytes by using transactivator of transcription (TAT)-mediated transduction with sEH mutant proteins. Cell death and hydrolase activity was lower in Arg287Gln EPHX2 mutants vs. nontransduced controls. Excess 14,15-EET and SEH inhibition did not improve cell survival in Arg287Gln mutants. In WT cells, the putative EET receptor antagonist, 14,15-EEZE, abolished the effect of 14,15-EET and sEH inhibition. Cotreatment with 14,15-EET and SEH inhibition did not provide increased protection. In vitro, STAT3 inhibition blocked 14,15-EET cytoprotection, but not the effect of SEH inhibition. However, STAT3 small interfering RNA (siRNA) abolished cytoprotection by 14,15-EET and sEH inhibition, but cells pretreated with JAK2 siRNA remained protected. In vivo, STAT3 inhibition abolished 14,15-EET-mediated infarct size reduction. In summary, the Arg287Gln mutation is associated with improved tolerance against ischemia in vitro, and inhibition of sEH preserves cardiomyocyte viability following OGD/RGR via an EET-dependent mechanism. In vivo and in vitro, 14,15-EET-mediated protection is mediated in part by STAT3. [ABSTRACT FROM AUTHOR]

Motoki A, Merkel MJ, Packwood WH, Cao Z, Liu L, Iliff J, Alkayed NJ, Van Winide DM. Soluble epoxide hydmlase inhibition and gene deletion are pmtective against myocardial ischemia-reperfusion injury in vivo. Am J Physiol Heart Circ Physiol 295: H2128-H2134, 2008. First published October 3, 2008; doi: 10.1152/ajpheart.00428.2008. -Soluble epoxide hydrolase (sEH) metabolizes epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids. EETs are formed from arachidonic acid during myocardial ischemia and play a protective role against ischemic cell death. Deletion of sEH has been shown to be protective against myocardial ischemia in the isolated heart preparation. We tested the hypothesis that sEH inactivation by targeted gene deletion or pharmacological inhibition reduces infarct size (I) after regional myocardial ischemia-reperfusion injury in vivo. Male C57BL\6J wildtype or sEH knockout mice were subjected to 40 mm of left coronary artery (LCA) occlusion and 2 h of reperfusion. Wild-type mice were injected intraperitoneally with 12-(3-adamantan-1-y1-ureido)-dodecanoic acid butyl ester (AUDA-BE), a sEH inhibitor, 30 mm before LCA occlusion or during ischemia 10 mm before reperfusion. 14,15EET, the main substrate for sEH, was administered intravenously 15 mm before LCA occlusion or during ischemia 5 mm before reperfusion. The EET antagonist 14,15-epoxyeicosa-5(Z)-enoic acid (EEZE) was given intravenously 15 mm before reperfusion. Area at risk (AAR) and I were assessed using fluorescent microspheres and tnphenyltetrazolium chloride, and I was expressed as I/AAR. I was significantly reduced in animals treated with AUDA-BE or 14,15EET, independent of the time of administration. The cardioprotective effect of AUDA-BE was abolished by the EET antagonist 14,15EEZE. Immunohistochemistry revealed abundant sEH protein expression in left ventricular tissue. Strategies to increase 14,15-EET, including sEH inactivation, may represent a novel therapeutic approach for cardioprotection against myocardial ischemia-reperfusion injury. [ABSTRACT FROM AUTHOR]