11-12-epoxy-5-8-14-eicosatrienoic-acid and Myocardial-Infarction

Exercise training (ET) is a safe and efficacious therapeutic approach for myocardial infarction (MI). Given the numerous benefits of exercise, exercise-induced mediators may be promising treatment targets for MI. C57BL/6 mice were fed 1-trifluoromethoxyphenyl-3-(1-propionylpiperidine-4-yl) urea (TPPU), a novel soluble epoxide hydrolase inhibitor (sEHI), to increase epoxyeicosatrienoic acid (EET) levels, for 1 week before undergoing MI surgery. After 1-week recovery, the mice followed a prescribed exercise programme. Bone marrow-derived endothelial progenitor cells (EPCs) were isolated from the mice after 4 weeks of exercise and cultured for 7 days. Angiogenesis around the ischaemic area, EPC functions, and the expression of microRNA-126 (miR-126) and its target gene Spred1 were measured. The results were confirmed in vitro by adding TPPU to EPC culture medium. ET significantly increased serum EET levels and promoted angiogenesis after MI. TPPU enhanced the effects of ET to reduce the infarct area and improve cardiac function after MI. ET increased EPC function and miR-126 expression, which were further enhanced by TPPU, while Spred1 expression was significantly down-regulated. Additionally, the protein kinase B/glycogen synthase kinase 3β (AKT/GSK3β) signalling pathway was activated after the administration of TPPU. EETs are a potential mediator of exercise-induced cardioprotection in mice after MI. TPPU enhances exercise-induced cardiac recovery in mice after MI by increasing EET levels and promoting angiogenesis around the ischaemic area.

Topics: 8,11,14-Eicosatrienoic Acid; Adaptor Proteins, Signal Transducing; Animals; Bone Marrow Cells; Cardiotonic Agents; Coronary Vessels; Disease Models, Animal; Endothelial Progenitor Cells; Enzyme Inhibitors; Epoxide Hydrolases; Gene Expression Regulation; Glycogen Synthase Kinase 3 beta; Male; Mice; Mice, Inbred C57BL; MicroRNAs; Myocardial Infarction; Neovascularization, Physiologic; Phenylurea Compounds; Physical Conditioning, Animal; Piperidines; Primary Cell Culture; Proto-Oncogene Proteins c-akt; Repressor Proteins; Signal Transduction

We previously demonstrated that several epoxyeicosatrienoic acids (EETs) produce reductions in myocardial infarct size in rats and dogs. Since a recent study demonstrated the release of opioids in mediating the antinociceptive effect of 14,15-EET, we hypothesized that endogenous opioids may also be involved in mediating the cardioprotective effect of the EETs. To test this hypothesis, we used an in vivo rat model of infarction and a rat Langendorff model. In the infarct model, hearts were subjected to 30 min occlusion of the left coronary artery and 2 h reperfusion. Animals were treated with 11,12-EET or 14,15-EET (2.5 mg/kg) alone 15 min before occlusion or with opioid antagonists [naloxone, naltrindole, nor-binaltorphimine (nor-BNI), and d-Phe-Cys-Tyr-d-Trp-Om-Thr-Pen-Thr-NH(2) (CTOP), a nonselective, a selective delta, a selective kappa, and a selective mu receptor antagonist, respectively] 10 min before EET administration. In four separate groups, antiserum to Met- and Leu-enkephalin and dynorphin-A-(1-17) was administered 50 min before the 11,12-EET administration. Infarct size expressed as a percent of the area at risk (IS/AAR) was 63.5 + or - 1.2, 45.3 + or - 1.0, and 40.9 + or - 1.2% for control, 11,12-EET, and 14,15-EET, respectively. The protective effects of 11,12-EET were abolished by pretreatment with either naloxone (60.5 + or - 1.8%), naltrindole (60.8 + or - 1.0%), nor-BNI (62.3 + or - 2.8%), or Met-enkephalin antiserum (63.2 + or - 1.7%) but not CTOP (42.0 + or - 3.0%). In isolated heart experiments, 11,12-EET was administered to the perfusate 15 min before 20 min global ischemia followed by 45 min reperfusion in control hearts or in those pretreated with pertussis toxin (48 h). 11,12-EET increased the recovery of left ventricular developed pressure from 33 + or - 1 to 45 + or - 6% (P < 0.05) and reduced IS/AAR from 37 + or - 4 to 20 + or - 3% (P < 0.05). Both pertussis toxin and naloxone abolished these beneficial effects of 11,12-EET. Taken together, these results suggest that the major cardioprotective effects of the EETs depend on activation of a G(i/o) protein-coupled delta- and/or kappa-opioid receptor.

Topics: 8,11,14-Eicosatrienoic Acid; Analgesics, Opioid; Animals; Disease Models, Animal; GTP-Binding Protein alpha Subunits, Gi-Go; Male; Myocardial Infarction; Myocardial Reperfusion Injury; Naloxone; Naltrexone; Narcotic Antagonists; Rats; Rats, Sprague-Dawley; Receptors, Opioid; Somatostatin

Previously, we demonstrated (17) that 11,12- and 14,15-epoxyeicosatrienoic acids (EETs) produce marked reductions in myocardial infarct size. Although it is assumed that this cardioprotective effect of the EETs is due to a specific interaction with a membrane-bound receptor, no evidence has indicated that novel EET antagonists selectively block the EET actions in dogs. Our goals were to investigate the effects of 11,12- and 14,15-EET, the soluble epoxide hydrolase inhibitor, 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA), and the putative selective EET antagonist, 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE), on infarct size of barbital anesthetized dogs subjected to 60 min of coronary artery occlusion and 3 h of reperfusion. Furthermore, the effect of 14,15-EEZE on the cardioprotective actions of the selective mitochondrial ATP-sensitive potassium channel opener diazoxide was investigated. Both 11,12- and 14,15-EET markedly reduced infarct size [expressed as a percentage of the area at risk (IS/AAR)] from 21.8 +/- 1.6% (vehicle) to 8.7 +/- 2.2 and 9.4 +/- 1.3%, respectively. Similarly, AUDA significantly reduced IS/AAR from 21.8 +/- 1.6 to 14.4 +/- 1.2% (low dose) and 9.4 +/- 1.8% (high dose), respectively. Interestingly, the combination of the low dose of AUDA with 14,15-EET reduced IS/AAR to 5.8 +/- 1.6% (P < 0.05), further than either drug alone. Diazoxide also reduced IS/AAR significantly (10.2 +/- 1.9%). In contrast, 14,15-EEZE had no effect on IS/AAR by itself (21.0 +/- 3.6%), but completely abolished the effect of 11,12-EET (17.8 +/- 1.4%) and 14,15-EET (19.2 +/- 2.4%) and AUDA (19.3 +/- 1.6%), but not that of diazoxide (10.4 +/- 1.4%). These results suggest that activation of the EET pathway, acting on a putative receptor, by exogenous EETs or indirectly by blocking EET metabolism, produced marked cardioprotection, and the combination of these two approaches resulted in a synergistic effect. These data also suggest that 14,15-EEZE is not blocking the mitochondrial ATP-sensitive potassium channel as a mechanism for antagonizing the cardioprotective effects of the EETs.

Topics: 8,11,14-Eicosatrienoic Acid; Adamantane; Animals; Blood Pressure; Cardiovascular Agents; Coronary Circulation; Diazoxide; Disease Models, Animal; Dogs; Dose-Response Relationship, Drug; Enzyme Inhibitors; Epoxide Hydrolases; Female; Heart Rate; Lauric Acids; Male; Mitochondria, Heart; Myocardial Infarction; Myocardium; Potassium Channels

Cytochrome P450 (CYP) epoxygenases and their arachidonic acid (AA) metabolites, the epoxyeicosatrienoic acids (EETs), have been shown to produce reductions in infarct size in canine myocardium following ischemia-reperfusion injury via opening of either the sarcolemmal K(ATP) (sarcK(ATP)) or mitochondrial K(ATP) (mitoK(ATP)) channel. In the present study, we subjected intact rat hearts to 30 min of left coronary artery occlusion and 2 h of reperfusion followed by tetrazolium staining to determine infarct size as a percent of the area at risk (IS/AAR, %). The results demonstrate that the two major regioisomers of the CYP epoxygenase pathway, 11,12-EET (2.5 mg/kg, iv) and 14,15-EET (2.5 mg/kg, iv) significantly reduced myocardial infarct size (IS/AAR, %) in rats as compared with control (41.9+/-2.3%, 40.9+/-1.2% versus 61.5+/-1.6%, respectively), whereas, a third regioisomer, 8,9-EET (2.5 mg/kg, iv) had no effect (55.2+/-1.4). The protective effect of pretreatment with 11,12- and 14,15-EETs was completely abolished (61.9+/-0.7%, 58.6+/-3.1%, HMR; 63.3+/-1.2%, 63.2+/-2.5%, 5-HD) in the presence of the selective sarcK(ATP) channel antagonist, HMR 1098 (6 mg/kg, iv) or the selective mitoK(ATP) channel antagonist, 5-HD (10 mg/kg, iv) given 10 min after 11,12- or 14,15-EET administration but 5 min prior to index ischemia. Furthermore, concomitant pretreatment with 11,12- or 14,15-EET in combination with the free radical scavenger, 2-mercaptopropionyl glycine (2-MPG), at a dose (20 mg/kg, iv) that had no effect on IS/AAR (57.7+/-1.3%), completely abolished the cardioprotective effect of 11,12- and 14,15-EETs (58.2+/-1.6%, 61.4+/-1.0%), respectively. These data suggest that part of the cardioprotective effects of EETs in rat hearts against infarction is the result of an initial burst of reactive oxygen species (ROS) and subsequent activation of both the sarcK(ATP) and mitoK(ATP) channel.

Topics: 8,11,14-Eicosatrienoic Acid; Adenosine Triphosphate; Animals; Male; Myocardial Infarction; Potassium Channels; Rats; Rats, Sprague-Dawley; Regional Blood Flow; Tiopronin