ISCHEMIA REPERFUSION & OXIDANT STRESS IN G6PD DEFICIENCY

项目3的总体目标是研究黑人缺血性心脏病（IHD）预后不成比例差的基本机制，并测试针对这些机制的治疗效果。患有IHD的黑人易受缺血和再灌注的影响，缺血和再灌注产生活性氧（ROS），导致心肌氧化损伤。 内源性心肌防御氧化应激主要由葡萄糖-6-磷酸脱氢酶（G6 PD）介导。G6 PD缺乏症是人类最常见的酶病，并且已知在黑人中特别普遍。此外，黑人也有高比例的盐敏感性高血压和心室肥大，这是IHD的两个常见危险因素。在SCOR项目的最后一个周期中，盐敏感性高血压被证明部分是由于ROS水平升高导致NO失活导致可用性降低。我们的中心假设是G6 PD缺乏加重了缺血-再灌注损伤，并可能部分解释了黑人IHD预后不良的原因。此外，继发于G6 PD缺乏的ROS水平增加可能加重盐敏感性高血压和肥大，并加重肥大心脏的缺血再灌注损伤。将在三个生理整合水平研究G6 PD缺陷的小鼠：完整动物、分离的灌注心脏和分离的肌细胞。在完整小鼠中，在冠状动脉结扎和再灌注后评估G6 PD缺乏对心血管系统的后果。在离体心脏中，将在缺血再灌注期间测量收缩和舒张功能，沿着高能磷酸盐代谢、戊糖磷酸盐通量和谷胱甘肽氧化还原状态的NMR光谱测量。在经历缺氧-复氧的分离的肌细胞中，收缩性的变化将与细胞钙和ROS水平通过荧光探针同时测量。将确定可能保护G6 PD缺陷心肌免受缺血-再灌注损伤的临床相关治疗（抗氧化剂、增加磷酸戊糖途径通量、长期运动训练）的疗效和作用机制。该项目的数据将提供有关心肌损伤基本机制的新信息，并确定黑人IHD的潜在治疗策略。

The overall goals of Project 3 are to investigate the basic mechanisms underlying the disproportionately poor prognosis in blacks with ischemic heart disease (IHD), and to test the efficacy of therapies targeted at these mechanisms. Blacks with IHD are subject to episodes of ischemia and reperfusion that generate reactive oxygen species (ROS), resulting in myocardial oxidant injury. Endogenous myocardial defense against oxidant stress is mediated primarily by glucose-6-phosphate dehydrogenase (G6PD). G6PD deficiency in the most common enzymopathy in humans, and is known to be especially prevalent in blacks. In addition, blacks also have a high rate of salt-sensitive hypertension and ventricular hypertrophy, two common risk factors for IHD. In the last cycle of this SCOR program, salt-sensitive hypertension was shown to be due, in part, to a reduced availability largely as a consequence of inactivation of NO by elevated levels of ROS. Our central hypothesis is that G6PD deficiency exacerbates injury from ischemia- reperfusion and may, in part, account for the worse prognosis in blacks with IHD. Furthermore, increased ROS levels secondary to G6PD deficiency may exacerbate salt-sensitive hypertension and hypertrophy, and worsens ischemia-reperfusion injury in hypertrophied hearts. Mice deficient in G6PD will be studied at three levels of physiologic integration: intact animals, isolated perfused hearts and isolated myocytes. In intact mice, the consequences of G6PD deficiency on the cardiovascular system will be assessed following coronary ligation and reperfusion. In isolated hearts, systolic and diastolic function will be measured during ischemia reperfusion, along with NMR spectroscopic measurements of high energy phosphate metabolism, pentose phosphate flux, and glutathione redox state. In isolated myocytes undergoing hypoxia-reoxygenation, changes in contractility will be measured simultaneously with cell calcium with ROS levels by fluorescent probes. The efficacy and mechanisms of action of clinically relevant treatment (antioxidants, increased pentose phosphate pathway flux, chronic exercise training) that may protect against ischemia-reperfusion injury in G6PD deficient myocardium will be determined. Data from this project will provide new information regarding the basic mechanisms underlying myocardial injury, as well as identify potential treatment strategies for blacks with IHD.