Effect of Drugs on Myocardial Hypoxia

描述(申请人提供)：本研究提案的目标是研究阿片受体激动剂在再灌流时和作为慢性治疗时对缺血/再灌注损伤提供保护的机制。我们推测，Delta和Kappa阿片受体激动剂在再灌流前给药时，通过激活促存活信号通路，包括PI3K/AKT/GSKbeta/ERK1/2轴(再灌流损伤、挽救激酶或风险通路)来提供心脏保护。对于慢性治疗，我们假设持续的心脏保护是由两种互补的机制介导的：1)上调心肌保护蛋白，包括12-LO、iNOS和COX-2(延迟诱导挽救途径或DISP途径)，以及2)诱导β2肾上腺素能受体导致腺酰环化酶抑制。总体而言，我们预测ATP敏感性钾通道(KATP)的肌膜亚型是触发，线粒体KATP通道是阿片受体诱导的心脏保护的终端效应器。我们的研究包括使用在体大鼠/小鼠脑梗塞模型和离体鼠全心缺血再灌注模型，在该模型中，梗死面积和左心室收缩功能的恢复分别作为缺血损伤的指标。具体的信号通路、心脏保护蛋白和受体亚型的参与将通过使用选择性药理探针、基因“敲除”小鼠、Western免疫印迹、放射配基结合分析以及记录肌膜(膜片钳记录的分离心肌细胞)和线粒体(记录线粒体脂双层中的KATP通道电流)KATP通道电流来评估。总而言之，这些研究结合了最先进的技术，提供了关于阿片受体激动剂保护缺血/再灌注损伤的机制的新信息。从这些研究中获得的信息有望导致治疗缺血性心脏病患者的新疗法。

DESCRIPTION (provided by applicant): The goal of this research proposal is to examine mechanisms by which opioid receptor agonists provide protection from ischemia/reperfusion injury when administered at the time of reperfusion and when administered as chronic therapy. We hypothesize that delta and kappa opioid receptor agonists confer cardioprotection when administered prior to reperfusion by activating pro-survival signaling pathways including the PI3K/akt/GSKbeta/ERK 1/2 axis (reperfusion injury salvage kinases or the RISK pathway). With chronic therapy, we hypothesize that sustained cardioprotection is mediated by two complementary mechanisms: 1) up-regulation of cardioprotective proteins including 12-LO, iNOS, and COX-2 (delayed inducible salvage pathway or the DISP pathway), and 2) induction of beta-2 adrenergic receptors resulting in inhibition of adenylyl cyclase. Overall, we predict that the sarcolemmal isoform of the ATP-sensitive potassium (KATP) channel is the trigger and the mitochondrial KATP channel is the end-effector of opioid receptor-induced cardioprotection. Our studies involve the use of an in vivo rat/mouse model of infarction and an isolated mouse heart model of global ischemia and reperfusion in which infarct size and recovery of left ventricular contractile function are used as indices of ischemic injury, respectively. The involvement of specific signaling pathways, cardioprotective proteins, and receptor subtypes will be assessed by using selective pharmacological probes, gene "knock-out" mice, Western immunoblotting, radioligand binding analysis, and recording of sarcolemmal (patch clamp recordings of isolated cardiac myocytes) and mitochondrial (recordings of KATP channel currents in mitochondrial lipid bi-layers) KATP channel currents. Collectively, these studies combine state-of-the-art techniques to provide new information regarding mechanisms by which opioid receptor agonists provide protection from ischemia/reperfusion injury. Information gained from these studies will hopefully lead to new therapies to treat patients with ischemic heart disease.