Dept. of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
Am J Physiol Heart Circ Physiol. 2010 Jun;298(6):H2201-7. doi: 10.1152/ajpheart.00815.2009. Epub 2010 Apr 16.
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.
我们之前的研究表明，几种环氧化物二十碳三烯酸（EETs）可减少大鼠和犬的心肌梗死面积。由于最近的一项研究表明阿片类物质的释放可介导 14,15-EET 的抗伤害作用，我们假设内源性阿片类物质也可能参与介导 EETs 的心脏保护作用。为了验证这一假设，我们使用了体内大鼠梗死模型和大鼠 Langendorff 模型。在梗死模型中，心脏经历 30 分钟的左冠状动脉闭塞和 2 小时的再灌注。动物在闭塞前 15 分钟用 11,12-EET 或 14,15-EET（2.5mg/kg）处理，或在用阿片类拮抗剂[纳洛酮、纳曲吲哚、诺比那嗪（nor-BNI）和 d-Phe-Cys-Tyr-d-Trp-Om-Thr-Pen-Thr-NH(2)（CTOP），一种非选择性、选择性 delta、选择性 kappa 和选择性 mu 受体拮抗剂]预处理前 10 分钟给予 EET。在四个单独的组中，Met-和 Leu-脑啡肽和 dynorphin-A-(1-17)的抗血清在给予 11,12-EET 前 50 分钟给予。梗死面积表示为危险区域（IS/AAR）的百分比分别为 63.5 + or - 1.2%、45.3 + or - 1.0%和 40.9 + or - 1.2%，分别为对照组、11,12-EET 和 14,15-EET。11,12-EET 的保护作用被纳洛酮（60.5 + or - 1.8%）、纳曲吲哚（60.8 + or - 1.0%）、nor-BNI（62.3 + or - 2.8%）或 Met-脑啡肽抗血清（63.2 + or - 1.7%）预处理所消除，但 CTOP（42.0 + or - 3.0%）没有。在离体心脏实验中，11,12-EET 在对照组或预先用百日咳毒素（48 小时）预处理的心脏中，在 20 分钟全缺血前 15 分钟给予灌流液，随后再灌注 45 分钟。11,12-EET 使左心室发展压从 33 + or - 1 增加到 45 + or - 6%（P < 0.05），并将 IS/AAR 从 37 + or - 4 降低到 20 + or - 3%（P < 0.05）。百日咳毒素和纳洛酮都消除了 11,12-EET 的这些有益作用。综上所述，这些结果表明，EETs 的主要心脏保护作用依赖于 G(i/o)蛋白偶联的 delta-和/或 kappa-阿片受体的激活。
