Hydrogen Peroxide and Flow-Induced Dilation of Human Coronary Microcirculation

作用于内皮细胞的剪切力会产生血管扩张。这可以说是最重要的 内皮细胞的生理扩张机制，几乎发生在每一个血管床上。我们最近的数据 提示冠心病患者的冠状动脉微动脉存在血流介导的扩张(FMD)。 通过一种新的机制发挥作用，涉及内皮细胞产生活性氧物种(ROS) 包括过氧化氢(过氧化氢)。令人惊讶的是，线粒体呼吸链在 人类心脏中的口蹄疫。这个应用程序的总体目标是检查来自 内皮到血管的研究有三个目标。1)我们将研究内皮细胞产生的机制 过氧化氢。冠状动脉疾病患者新鲜冠状小动脉和培养的人冠状动脉 微血管组织和导管动脉内皮细胞进行比较。我们将追求刺激 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ROS释放机制和rac1的激活。2)使用一种新的生物检测技术来评估 血管扩张和平滑肌钾通道开放，我们将鉴定血管内皮细胞来源 导致扩张的超极化因子(EDHF)。花生四烯酸代谢产物和过氧化氢都是 对于口蹄疫来说是必要的，但初步研究表明过氧化氢是可转移的扩张剂。3)我们将 确定过氧化氢诱导扩张的机制，检验过氧化氢直接作用于 PKG1通过半胱氨酸氧化，产生激活的二硫键二聚体形式的酶。这些目标跨越了 广泛的、临床相关的氧化还原信号通路，从内皮细胞过氧化氢的形成到过氧化氢的释放 可转移的血管舒缩物质，以了解其对潜在的平滑肌细胞的作用机制。 这些目标共同解决了一种新的内皮依赖性扩张机制，包括 线粒体产生的ROS，到目前为止只在人类心脏中有报道。结果应确定新的链接 在调节重要生理功能的细胞机械转导、呼吸和氧化还原信号中 小动脉血管扩张等事件，负责组织灌流。与人类的直接关联 慢性冠状动脉疾病为理解这种机械性方法提供了坚实的基础 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.