Hydrogen Peroxide and Flow-Induced Dilation of Human Coronary Microcirculation

切应力作用于内皮细胞产生血管舒张。这可以说是最重要的 生理内皮机制的扩张，并发生在几乎每一个血管床。我们最近的数据 表明冠状动脉疾病患者冠状动脉中发生了血流介导的扩张（FMD）， 通过一种涉及内皮细胞产生活性氧（ROS）的新机制发挥作用 包括过氧化氢（H2 O2）。令人惊讶的是，线粒体呼吸链在 心脏里的口蹄疫。本申请的总体目标是检查FMD信号序列， 内皮细胞对平滑肌的研究3个目的。1)我们将研究内皮生产的机制， 过氧化氢使用来自患有冠状动脉疾病的受试者的新鲜人冠状动脉和培养的人 来自微血管组织和导管动脉的内皮细胞用于比较。我们将追求令人兴奋的 初步数据表明线粒体和NADPH氧化酶都参与其中，可能是通过ROS- 诱导的ROS释放机制和Rac 1的激活。2)使用新的生物测定技术来评估 血管舒张和平滑肌钾通道开放，我们将确定内皮源性 负责扩张的超极化因子（EDHF）。花生四烯酸代谢物和H2 O2都是 但初步研究指出H2 O2是可转移的扩张剂。3)我们将 确定H2 O2诱导扩张的机制，检查H2 O2直接作用于 PKG 1通过半胱氨酸氧化，产生酶的活化二硫键二聚体形式。这些目标涵盖了 从内皮H2 O2形成到H2 O2释放的广泛的临床相关氧化还原信号通路， 可转移的血管活性物质，其对底层平滑肌细胞的作用机制。 总的来说，这些目标涉及内皮依赖性舒张的新机制， 线粒体产生ROS，迄今为止仅在人类心脏中报道。结果应确定新的链接 在调节重要生理功能的细胞机械传导、呼吸和氧化还原信号传导中， 诸如小动脉血管舒张的事件，负责组织灌注。与人类的直接关系 慢性冠状动脉疾病为这种机制的理解提供了坚实的基础 微血管反应性

Shear stress acting on endothelial cells produces vasodilation. This is arguably the most important physiological endothelial mechanism of dilation and occurs in virtually every vascular bed. Our recent data indicate that flow-mediated dilation (FMD) occurs in coronary arterioles from patients with coronary disease but operates through a novel mechanism involving endothelial production of reactive oxygen species (ROS) including hydrogen peroxide (H2O2). Surprisingly the mitochondrial respiratory chain plays a necessary role in FMD in the human heart. The overall goal of this application is to examine the FMD signaling sequence from endothelium to smooth muscle studying 3 aims. 1) We will examine the mechanism of endothelial production H2O2. using fresh human coronary arterioles from subjects with coronary disease and cultured human endothelial cells from both microvascular tissue and conduit arteries for comparison. We shall pursue exciting preliminary data that indicate both mitochondria and NADPH oxidase are involved, possibly through a ROS- induced ROS release mechanism and activation of Rac1. 2) Using a novel bioassay technique to assess vasodilation and smooth muscle potassium channel opening, we shall identify the endothelial derived hyperpolarizing factor (EDHF) responsible for dilation. Both arachidonic acid metabolites and H2O2 are necessary for FMD, but preliminary studies point to H2O2 as the transferable dilator agent. 3) We shall determine the mechanism of H2O2 -induced dilation, examining the novel hypothesis that H2O2 directly acts on PKG1¿ by cysteine oxidation, yielding an activated disulfide dimeric form of the enzyme. These goals span a broad, clinically relevant redox signaling pathway from endothelial H2O2 formation, to H2O2 release as a transferable vasomotor substance, to its mechanism of action on underlying smooth muscle cells. Collectively these aims address a novel mechanism of endothelium-dependent dilation involving mitochondrial generation of ROS, thus far reported only in human hearts. Results should identify new links among cellular mechanotransduction, respiration, and redox signaling that regulate important physiological events such as arteriolar vasodilation, responsible for tissue perfusion. The direct relevance to humans with chronic coronary disease provides a strong foundation for this mechanistic approach to understanding microvascular reactivity.