Flow-induced coronary vasospasm in diabetic patients

描述（由申请人提供）：2型糖尿病（T2-DM）患者无复流现象的患病率较高，无复流现象是经皮冠状动脉介入治疗（PCI）的一种知之甚少且不可预测的并发症，尽管成功治疗了心外膜冠状动脉的闭塞性病变，但流向远端微血管床的血流仍然减少。目前预防无复流的治疗干预是无效的。与此应用相关的初步观察导致了我的主要假设，即糖尿病患者的小冠状动脉对流量突然增加表现出矛盾的收缩，这种变化导致无复流。我建议，RhoA依赖性的共定位酶I和eNOS导致减少NO合成和减少NO介导的扩张，以响应流量在T2-DM。我还假设，刺激血小板内皮细胞粘附分子-1（Pecam-1，称为内皮中的主要流量传感器），增加管腔内流量，升高内皮[Ca 2 +]i，这通过诱导磷脂酶A2和花生四烯酸释放，导致T2-DM患者冠状血管中血栓烷A2的产生增加。为了验证这些假设，我的目标是从接受心脏手术的T2-DM患者的（废弃的）心房附件中分离小冠状动脉血管。使用小血管压力肌描记术和视频显微镜，在存在特定信号通路抑制剂的情况下，测量暴露于腔内流量突然增加的孤立的冠状小动脉（< 100 5 m）的直径变化。为了研究eNOS和Pecam-1的（共）定位以及检测Pecam-1的空间分布和相互作用，将在分离的、加压的冠状动脉和培养的冠状动脉内皮细胞中使用激光扫描共聚焦显微镜和荧光共振能量转移方法。此外，将在完整的加压冠状动脉中用Fura-2荧光测量血流诱导的内皮[Ca 2 +]i变化，以揭示亚细胞水平[Ca 2 +]i升高的空间差异。如果在项目过程中获得的结果支持我的假设，这将是第一次描述的Pecam-1耦合收缩前列腺素类生产在人类冠状动脉。研究结果还将提供一种新的机制，通过这种机制，Pecam-1的空间分布决定了T2-DM中释放的血管活性介质的性质，以增加血流。本项目中获得的数据也将有助于开发有效治疗策略的新途径，例如在PCI时使用前列腺素抑制剂，以预防T2-DM患者的无复流。

DESCRIPTION (provided by applicant): Patients with type 2 diabetes mellitus (T2-DM) have higher prevalence of no-reflow phenomenon - a poorly understood and unpredictable complication of percutaneous coronary intervention (PCI) in which diminished blood flow to distal microvascular beds persists despite the successful treatment of the occlusive lesion of the epicardial coronary artery. Current therapeutic interventions to prevent no reflow are ineffective. Preliminary observations related to this application led to my main hypothesis that small coronary arteries of diabetic patients exhibit a paradoxical constriction to sudden increases in flow, an alteration, which contributes to no reflow. I propose that RhoA-dependent co-localization of arginase I and eNOS leads to reduced NO synthesis and diminished NO-mediated dilatation in response to flow in T2-DM. I also hypothesize that stimulation of platelet endothelium cell adhesion molecule -1 (Pecam-1, known as primary flow sensor in endothelium) with increases in intraluminal flow elevates endothelial [Ca2+]i, which via inducing phospholipase A2 and arachidonic acid release leads to enhanced production of thromboxane A2 in coronary vessels of T2-DM patients. To test these hypotheses, I aim to isolate small coronary vessels from the (discarded) atrial appendages of patients with T2-DM undergoing cardiac surgery. Using small vessel pressure myography and videomicroscopy, diameter changes of the isolated, coronary arteriole (< 100 5m) exposed to sudden increase in intraluminal flow will be measured in the presence of inhibitors of specific signaling pathways. To investigate (co)localization of eNOS and arginase I as well as to detect spatial distribution and interaction of Pecam-1 laser scanning confocal microscopy and fluorescence resonance energy transfer approaches will be used in isolated, pressurized coronary arteries and coronary endothelial cells in culture. Moreover, flow-induced changes in endothelial [Ca2+]i will be measured with Fura-2 fluorescence in intact, pressurized coronary arterioles to reveal spatial differences of [Ca2+]i elevations at subcellular level. Should the results obtained in the course of the project support my hypothesis this will be the first description of Pecam-1-coupled constrictor prostanoid production in human coronary arteries. Results will also provide a novel mechanism by which spatial distribution of Pecam-1 determines the nature of vasoactive mediators released to increase in flow in T2-DM. Data obtained in this project will also help to develop novel avenues for effective therapeutic strategies, such as the use of prostanoid inhibitors at the time of PCI, to prevent no reflow in patients with T2-DM.