HETEROGENEITY OF CORONARY ARTERY VASOMOTION

这些研究评估了有无冠状动脉血管运动的活性。 冠状动脉疾病。研究将首先解决这样一个假设： 不同冠脉节段的血管运动反应是不同的 通过以下方式在每个节段中主导不同的血管扩张机制 表征近端电导和远端电阻的响应 冠状动脉对内源性和外源性血管活性物质的作用。近端 冠状动脉血管运动将由数字维度晶体测量 定量血管造影术对远端阻力血管的影响将是 通过使用长期植入的流动探头或 多普勒血流导管(患者)。对壁内电导的影响 动脉将被评估为峰值充血血流的变化(患者和 狗)和跨壁血流分布(狗)在最大扩张期间 阻力血管。然后，研究将解决这一假设，即 血管内皮主要介导和/或调节血管舒缩反应 近端和壁间电导血管，并提供内在的 血流传感机制，介导均匀的血管扩张 血流增加；内皮功能障碍将抑制诱导的血流 传导动脉扩张与限制心肌灌注 在特定的生理压力下。内皮功能障碍将会是 由(I)体内抑制剂(亚甲蓝，ETYA)和(Ii)诱导 临床相关病理情况(缺血/再灌注，急性 高血压或动脉粥样硬化)，已被证实可改变 内皮细胞介导的反应。近端的孤立节段 冠状动脉和生物测定准备也将用于恭维 完整的生理准备和评估异常 内皮术后内皮衍生松弛因子的产生 功能障碍。最后，研究将检验硝酸盐的假设 耐受性主要发生在近端电导而不是远端电导 阻力血管.与其他鸟粪酸盐激活剂的交叉公差 不存在环化酶(EDRF和心钠素)。这些 研究将进一步阐明冠心病的基本机制 生理状态下的血管运动。

These studies assess coronary vasomotor activity with and without coronary artery disease. Studies will first address the hypothesis that vasomotor responses of different coronary segments are heterogenous due to predominance of different vasodilator mechanisms in each segment by characterizing responses of proximal conductance and distal resistance coronary vessels to endogenous and exogenous vasoactive agents. Proximal coronary vasomotion will be measured by dimension crystals in digital quantitative angiography. Effects on distal resistance vessels will be assessed by flow changes using chronically implanted flow probes or Doppler flow catheters (patients). Effects on intramural conductance arteries will be assessed as changes in peak hyperemic flow (patients and dogs) and transmural flow distribution (dogs) during maximal dilation of resistance vessels. Studies will then address the hypothesis that the endothelium mediates and/or modulates vasomotor responses primarily in proximal and intramural conductance vessels and provides an intrinsic flow sensing mechanism that mediates uniform vasodilation in response to flow increases; endothelial dysfunction will inhibit flow induced dilation of the conductance arteries and limit myocardial perfusion during certain physiologic stresses. Endothelial dysfunction will be induced by (i) in vivo inhibitors (methylene blue, ETYA) and (ii) clinically relevant pathologic conditions (ischemia-/reperfusion, acute hypertension or atherosclerosis) which have been demonstrate to alter endothelial mediated responses. Isolated segments of the proximal coronary artery and bioassay preparations will also be used to compliment intact physiological preparations and to assess abnormalities in endothelium-derived relaxing factor (EDRF) production after endothelial dysfunction. Finally, studies will test the hypothesis that nitrate tolerance occurs primarily in proximal conductance rather than distal resistance vessels; cross tolerance with other activators of guanylate cyclase (EDRF and atrial natriuretic peptide) does not occur. These studies will further clarify fundamental mechanisms of coronary vasomotion during physiologic conditions.