RELATIONS BETWEEN FLOW STRUCTURE AND VASCULAR PATHOPHYSIOLOGICAL CHANGES IN THE CARDIOVASCULAR SYSTEM --STUDIED BY ULTRASONIC DIGITAL FLOW IMAGING SYSTEM--

特定血流动力学在动脉粥样硬化的发生和发展中起着重要作用。为了从局部血流动力学角度阐明动脉粥样硬化的潜在机制，我们通过高频多门多普勒血流仪评估了犬动脉壁剪切应力的分布，这使我们能够测量体内血管的瞬时血流速度分布。然后，我们用超微结构形态测量法研究了内皮细胞壁剪应力与微丝束数量的定量关系。5只狗左开胸后，将多普勒换能器以固定角度（60度）置于左冠状动脉前降支（LAD）、锁骨下动脉（SA）和胸降主动脉（DA）上，记录血流速度剖面。壁面剪切应力由边界层的速度梯度和血液的运动粘度的乘积确定。多普勒检查后，在恒压（100 mmHg）下灌注固定血管，并在x17720照片上纵向和横向进行0.3mm长的超微结构形态学分析。数据总结如下表1和表2所示。与SA和DA相比，LAD的峰值壁剪应力显著降低。然而，微丝束面积与内皮细胞面积之比（F/C）在LAD中明显大于SA和DA。因此，这些结果表明，在生理条件下，内皮细胞中与肌动蛋白丝应力纤维相容的微丝束的数量似乎不仅仅由壁剪切应力决定。与其他动脉相比，冠状动脉内皮细胞的细胞骨架结构被认为是非常特异性的，这一发现似乎有助于评估冠状动脉的病理。少

Specific flow dynamics would play a significant role in the initiation and development of atherosclerosis. To elucidate the underlying mechanism of the atherogenesis with regard to local flow dynamics, we assessed the distribution of the wall shear stress in canine arteries by the high frequency multigate Doppler flowmetry, which allowed us to measure the instantaneous flow velocity profile in in vivo vessels. Then, we investigated the quantitative relation of the wall shear stress with the amount of the microfilament bundle in the endothelial cell as assessed by ultrastructual morphometry. After the left thoracotomy, the Doppler transducer was placed on the left anterior descending coronary artery (LAD), subclavian artery (SA), and thoracic descending aorta (DA) at the fixed angle (60 degrees), and the recording of flow velocity profile was performed in 5 dogs. The wall shear stress was determined as a product of the velocity gradient in the boudary layer and the kinematic viscocity o … More f the blood. After the Doppler examination, the studied vessels were perfusion-fixed under the constant pressure (100 mmHg), and the ultrastructural morphometric analysis was performed longitudinally and transversely in the length of 0.3mm in x17720 photos. The data are summerized in the following tables 1 and 2.Peak wall shear stress was signigicantly lower in LAD compared with those in SA and DA. However, the F/C ratio, the ratio of the area of microfilament bundle to the area of endothelial cell, was significantly greater in LAD than those in SA and DA. Thus, these results suggest that in physiological conditions the amount of the microfilament bundle in the endothelial cell, which is compatible with actin filament stress fiber, seems not to be determined only by the wall shear stress. The cytoskeletal structure of the coronary arterial endothelial cell is considered to be quite specific when compared with that in other artery, and this finding seems to be helpful in assessing the pathology of the coronay artery. Less