Roles of Endothelial and Smooth Muscle KATP Channels in Myocardial Ischemic Injury

总结 肌膜ATP敏感性K+（KATP）通道在心脏中大量表达。几个团体已经 现在确定了这些通道在介导心脏保护对抗缺血性损伤中的关键作用， 参与缺血预适应的保护机制。在心中有几个不同的 KATP通道的亚型和在缺血和再灌注过程中的作用知之甚少。特别 感兴趣的是存在于冠状动脉平滑肌（SM）和冠状动脉内皮细胞（ECV）中的KATP通道亚型。 细胞（EC）。人们越来越关注这些冠状动脉通道作为血流调节的靶点， 心脏保护，但它们相对知之甚少。SM和EC KATP通道不同于 心室KATP通道，它们也彼此不同。一个主要的障碍，我们的理解， 它们在复杂事件如心肌缺血期间各自的作用是目前可用的 资源专门研究这两个通道亚型。我们创造了新的遗传小鼠模型 它可以区分KATP通道亚型，并显示其中一种ECKATP通道 在缺血/再灌注期间强烈参与心肌保护。拟议研究的目标是 系统地研究EC和SM KATP通道亚型在调节冠状动脉粥样硬化中的作用。 血流量、缺血期间的保护和对缺血预处理的保护反应。我们 假设EC和SM KATP通道亚型都参与了冠状动脉血液的调节 流动和心脏保护，但通过明显不同的机制。使用新的和经过验证的 在条件性敲除小鼠中，我们将特异性靶向EC或SM KATP通道亚型。拟议的研究 有三个目标。在目的1中，我们将研究这两种冠状动脉KATP通道亚型在血液中的作用。 在局部缺血期间流动。我们将使用隔离的加压微血管和隔离的灌注心脏， 正常、缺氧和缺血状态。我们还将研究EC和SM KATP通道的作用， 心肌“无复流”现象目的2将研究EC和SM KATP通道在 使用体内小鼠I/R模型进行心肌保护，并研究调节梗死的途径 发展目的3探讨EC和SM KATP通道亚型在缺血性脑损伤中的作用 使用体内鼠I/R模型和细胞测定进行预处理。我们还将审查这些贩运活动， KATP通道亚型作为一种潜在的保护机制，并探讨分子信号通路 涉案这个多研究者的建议结合了三个高度成熟的研究者的专业知识; Lefer在体内心脏缺血/再灌注模型方面的广泛专业知识，以及Coetzee博士在 用电生理学、生物化学和分子方法研究KATP通道， 在研究血管KATP通道的分子信号通路的专业知识。拟议的研究将 为冠状动脉KATP通道亚型的独特功能提供了重要的分子见解， 病理生理条件。

SUMMARY Sarcolemmal ATP-sensitive K+ (KATP) channels are abundantly expressed in the heart. Several groups have now identified a key role for these channels in mediating cardioprotection against ischemic injury and their participation in the protective mechanism of ischemic preconditioning. In the heart there several different subtypes of KATP channels and little is known about the roles during ischemia and reperfusion. Of particular interest are the KATP channel subtypes present in the coronary smooth muscle (SM) and coronary endothelial cells (EC). There is increasing focus on these coronary channels as a target for blood flow regulation and cardioprotection, yet they are relatively poorly understood. The SM and EC KATP channels are distinct from ventricular KATP channels and they are also distinct from each other. A major barrier to our understanding of their respective roles during a complex event such as myocardial ischemia is the lack of currently available resources specifically to study these two channel subtypes. We have generated novel genetic mouse models that can distinguish these subtypes of KATP channels and show with one of these that EC KATP channels strongly participate in myocardial protection during ischemia/reperfusion. The goal of the proposed studies is systematically to examine the role(s) of the EC and SM KATP channel subtypes in the regulation of coronary blood flow, protection during ischemia and the protective response to ischemic preconditioning. We hypothesize that both EC and SM KATP channel subtypes contribute to the regulation of coronary blood flow and cardioprotection, but through distinctly different mechanisms. Using novel and validated conditional knockout mice, we will specifically target EC or SM KATP channel subtypes. The proposed studies have three Aims. In Aim 1, we will investigate the roles of these two coronary KATP channel subtypes in blood flow during ischemia. We will use isolated, pressurized microvessels and isolated, perfused hearts under normal, hypoxic and ischemic conditions. We will additionally investigate the role of EC and SM KATP channels in the myocardial “no-reflow” phenomenon. Aim 2 will investigate the roles of EC and SM KATP channels in myocardial protection using an in vivo murine I/R model and investigate pathways that regulate infarct development. Aim 3 will investigate the contribution of EC and SM KATP channel subtypes during ischemic preconditioning using an in vivo murine I/R model and cellular assays. We will also examine trafficking of these KATP channel subtypes as a potential protective mechanism and investigate molecular signaling pathways involved. This multi-investigator proposal combines the expertise of three highly established investigators; Dr. Lefer’s extensive expertise with in vivo cardiac ischemia/reperfusion models, and Dr. Coetzee’s track record of studying KATP channels with electrophysiological, biochemical and molecular approaches and Dr. Tinker’s expertise in studying molecular signaling pathways in vascular KATP channels. The proposed studies will provide important molecular insights into the unique functions of coronary KATP channel subtypes under pathophysiological conditions.