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）不成比例预后不良的基本机制，并测试针对这些机制的治疗效果。患有IHD的黑人容易发生缺血和再灌注发作，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（G6PD）介导。G6PD缺乏症是人类最常见的酶病，在黑人中尤为普遍。此外，黑人患盐敏感性高血压和心室肥厚的比例也很高，这是IHD的两个常见危险因素。在这个SCOR项目的最后一个周期中，盐敏感性高血压的部分原因是由于活性氧水平升高导致NO失活而导致可用性降低。我们的中心假设是G6PD缺乏症加重了缺血-再灌注损伤，可能部分解释了黑人IHD患者预后较差的原因。此外，继发于G6PD缺乏的ROS水平升高可能加剧盐敏感性高血压和肥厚，加重肥厚心脏的缺血再灌注损伤。G6PD缺失小鼠将在三个生理整合水平上进行研究：完整的动物、分离的灌注心脏和分离的肌细胞。在完整小鼠中，G6PD缺乏对心血管系统的影响将在冠状动脉结扎和再灌注后进行评估。在离体心脏中，将在缺血再灌注期间测量收缩和舒张功能，以及核磁共振光谱测量高能磷酸盐代谢、戊糖磷酸盐通量和谷胱甘肽氧化还原状态。在缺氧再氧化的离体肌细胞中，通过荧光探针同时测量细胞钙和ROS水平的收缩性变化。临床相关治疗（抗氧化剂、增加戊糖磷酸通路通量、慢性运动训练）对G6PD缺陷心肌缺血-再灌注损伤的保护作用和机制将被确定。该项目的数据将为心肌损伤的基本机制提供新的信息，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.