Cytochrome P450 Eicosanoids and Myocardial Injury

描述（由申请人提供）：我们的实验室已经证明花生四烯酸（AA）代谢的几种环氧合酶（考克斯）和脂氧合酶（LOX）产物在缺血再灌注犬心肌中产生心脏保护作用，例如PGI 2、PGE 1和12-HETE。 然而，关于AA代谢的另一个主要途径，细胞色素P-450（CYP）途径的产物的心脏效应的数据很少。 在一个完善的犬心肌梗死模型和离体兔心肌细胞中，我们假设AA的代谢产物在缺血和再灌注期间释放，并通过开放和/或阻断心肌细胞中ATP敏感性（KATP）或钙激活钾（Kca）通道来产生心脏保护或增强心脏损伤。 初步结果表明，在冠状动脉闭塞和再灌注后，增加环氧二十碳三烯酸（ESTs），二羟基二十碳三烯酸（DHSTs）和20-羟基二十碳四烯酸（20-HETE）发生在闭塞结束时和整个再灌注，并通过阻断它们的形成两个非特异性ESTs抑制剂，心肌梗死面积显着减少。 此外，我们有初步的数据表明，外源性管理的20-HETE的结果在犬心脏梗死面积的增加。 因此，基于这些有趣的结果，我们将研究的作用和细胞机制，其中ESTA，DHESTA和20-HETE调节心肌梗死的体内模型和体外模型的缺氧-复氧心肌损伤。 具体来说，我们将确定和定量的区域异构体EclO，DHClO和20-HETE，由心脏以及表达的EclO亚型，在犬心脏缺血再灌注损伤的反应。 第二，我们将研究在缺血-再灌注犬心肌和暴露于缺氧-再给氧的离体成年兔心肌细胞中，β代谢物对KATP通道和KCa通道的作用以及所涉及的主要β途径。 最后，我们将研究考克斯和/或LOX途径与缺血-再灌注和缺氧-再给氧过程中的cAMP途径的相互作用。 我们在完善的细胞和动物模型中使用综合生理学，药理学，化学和分子生物学是鉴定缺血再灌注损伤中β通路作用的有力方法。

DESCRIPTION (provided by applicant): Several cyclooxygenase (COX) and lipoxygenase (LOX) products of arachidonic acid (AA) metabolism have been shown by our laboratory to produce a cardioprotective effect in the ischemicreperfused canine myocardium, examples being PGI2, PGE1 and 12-HETE. However, very little data exist concerning the cardiac effects of the products of the other major pathway of AA metabolism, the cytochrome P-450 (CYP) pathway. In a well-established model of canine myocardial infarction and in isolated rabbit cardiomyocytes, we hypothesize that the CYP metabolites of AA are released during ischemia and reperfusion and produce cardioprotection or enhance cardiac injury via the opening and/or blockade of ATP-sensitive (KATP) or calcium-activated potassium (Kca) channels in cardiac myocytes. Preliminary results indicate that during coronary artery occlusion and following reperfusion that increases in epoxyeicosatrienoic acids (EETs), dihydroxyeicosatrienoic acids (DHETs) and 20-hydroxyeicosatetraenoic acid (20-HETE) occur at the end of occlusion and throughout reperfusion and that by blocking their formation by two nonspecific CYP inhibitors, a marked reduction in myocardial infarct size occurred. In addition, we have preliminary data to suggest that exogenous administration of 20-HETE results in an increase in infarct size in the canine heart. Therefore, based on these intriguing results, we will study the role and cellular mechanisms by which the EETs, DHETs and 20-HETE modulate myocardial injury in an in vivo model of infarction and an in vitro model of hypoxia-reoxygenation. Specifically, we will identify and quantify the regioisomeric EETs, DHETs and 20-HETE that are produced by the heart as well as the CYP isoforms that are expressed in response to ischemia-reperfusion injury in dog hearts. Secondly, we will investigate the roles that CYP metabolites have on KATP channels and Kca channels in the ischemic-reperfused dog myocardium and on isolated adult rabbit cardiac myocytes exposed to hypoxia-reoxygenation and the major CYP pathways involved. Finally, we will investigate the interaction of the COX and/or LOX pathways with the CYP pathway during ischemia-reperfusion and hypoxia-reoxygenation. Our use of integrative physiology, pharmacology, chemistry and molecular biology in well-established cell and animal models is a powerful approach for identifying the role that the CYP pathway serves in ischemia-reperfusion injury.