White K C, Kavanaugh J F, Wang D M, Tarbell J M
Department of Chemical Engineering, Pennsylvania State University, University Park 16802-4400.
Circ Res. 1994 Oct;75(4):637-49. doi: 10.1161/01.res.75.4.637.
Vasoactive drugs are known to affect impedance (pressure/flow) and vessel wall motion in arteries. The nonlinear theory of oscillatory flow in straight elastic vessels indicates that wall shear rate is affected by changes in impedance phase angle and wall motion. To test whether wall shear rate depends on impedance phase angle and wall motion in vivo, wall shear rate was measured in the abdominal aorta of anesthetized dogs by using a flush-mounted hot-film anemometer, and the hemodynamic state was characterized by pressure, flow, and vessel dimension measurements. Vasodilators (nitroprusside and isoproterenol) and vasoconstrictors (angiotensin II and norepinephrine) were administered acutely, and the responses of wall shear rate and hemodynamics were determined. In the control state (no drugs), peak wall shear rate was 1835 +/- 153 s-1 (mean +/- SEM). The vasodilators induced large increases in impedance phase angle and wall motion concomitant with large increases in peak wall shear rate (62.4 +/- 20.4% for nitroprusside and 68.9 +/- 28.3% for isoproterenol), which were not predicted accurately by Womersley's theory of oscillatory flow in a rigid vessel or the nonlinear theory of oscillatory flow in an elastic vessel, with measured flow and vessel dimension used as inputs. The vasoconstrictors induced small decreases in impedance phase angle and wall motion and small changes in peak wall shear rate (increase, 30.5 +/- 8.0% for norepinephrine; decrease, 18.2 +/- 7.1% for angiotensin II), which were predicted accurately by Womersley's theory. The present study shows that vasoactive drugs, particularly vasodilators, can have significant effects on wall shear rate (stress) in the abdominal aorta that appear to be related to changes in impedance phase angle and vessel wall motion. However, the effects on wall shear rate are not predicted accurately by straight-tube theory.
已知血管活性药物会影响动脉中的阻抗（压力/流量）和血管壁运动。直弹性血管中振荡流的非线性理论表明，壁面剪切速率受阻抗相角和壁面运动变化的影响。为了测试体内壁面剪切速率是否取决于阻抗相角和壁面运动，使用嵌入式热膜风速仪在麻醉犬的腹主动脉中测量壁面剪切速率，并通过压力、流量和血管尺寸测量来表征血流动力学状态。急性给予血管扩张剂（硝普钠和异丙肾上腺素）和血管收缩剂（血管紧张素II和去甲肾上腺素），并确定壁面剪切速率和血流动力学的反应。在对照状态（未用药）下，峰值壁面剪切速率为1835±153 s-1（平均值±标准误）。血管扩张剂使阻抗相角和壁面运动大幅增加，同时峰值壁面剪切速率也大幅增加（硝普钠为62.4±20.4%，异丙肾上腺素为68.9±28.3%），使用测量的流量和血管尺寸作为输入时，刚性血管中振荡流的沃默斯利理论或弹性血管中振荡流的非线性理论均无法准确预测这些变化。血管收缩剂使阻抗相角和壁面运动小幅降低，峰值壁面剪切速率变化较小（去甲肾上腺素增加30.5±8.0%；血管紧张素II降低18.2±7.1%），沃默斯利理论可准确预测这些变化。本研究表明，血管活性药物，尤其是血管扩张剂，可对腹主动脉中的壁面剪切速率（应力）产生显著影响，这似乎与阻抗相角和血管壁运动的变化有关。然而，直管理论无法准确预测对壁面剪切速率的影响。
