Endothelium-dependent and -independent responses of coronary arteriole to pulsatile mechanical stress in vivo

我们组织这个项目是为了更好地了解脉状动脉在搏动机械应力下内皮依赖和独立调节的生理重要性。以下是本项目的主要发现。借助针-探头CCD活体显微镜和冠状动脉灌注系统，我们评估了冠状动脉对冠状动脉灌注压力降低的反应。脉冲性跨壁小动脉压力有助于小动脉扩张，以响应冠状动脉灌注压力的降低。同时，通过降低灌注压减少冠状动脉流量，舒张时间分数升高。这些与搏动相关的血管舒张和舒张灌注时间的调节可以为低灌注压下特别是心内膜下心肌的供需匹配提供重要的调节机制。

We organized this project in order to provide a better understanding of the physiological importance of the endothelium-dependent and -independent regulations of coronary arteriole under pulsatile mechanical stress. Followings are the major findings this project.With aids of needle-probe CCD intravital microscopy and coronary perfusion system, we evaluated the behavior of the coronary arterioles in response to a reduction of coronary perfusion pressure. Pulsatile transmural pressure of the arterioles contributed to the arteriolar dilation in response to a decrease in coronary perfusion pressure. At the same time, diastolic time fraction increased when coronary flow was reduced by lowering perfusion pressure. These pulsation-related vasodilation and modulation of diastolic perfusion time can provide an important regulatory mechanism to match supply and demand of the myocardium at low perfusion pressure, especially in the subendocardium.