Analysis of Blood Flow Dynamics in Cerebral Microvessels by a fiber-Optic Laser-Doppler Anemometer Microscope

光纤激光多普勒风速计显微镜分析脑微血管血流动力学

• 批准号: 08671627
• 负责人: SEKI Junji
• 金额: $ 1.41万
• 依托单位: National Cardiovascular Center Research Institute
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08671627/
• 关键词: Brain Pial Microvessels; Laser-Doppler Anemometer; Amplitude of Pulsation; Intravascular Pressure; Nitric Oxide; Wall Shear Stress; Vessel Wall Elasticity; Intracranial Pressure; Transmural Pressure; モデル解析

This research projecto was aimed to analyze the blood flow dynamics undr the various pathological conditions using our developed fiber-optic laser-Doppler anemometer microscope (FLDAM). In particular, effects of incresed intracranial pressure on the pulse wave propagation along the pial arteriolar network and effects of nitric oxide on the velocity distributions in the pial microvessels were studied.To observe the brain pial microcirculation, a closed cranial window was created on the parietal region of the rats. The red cell velocity in single pial microvessels was measured by the FLDAM.The internal pressure of the window, which is equal to the intracranial pressure, was changed between 0 and 50 mmHg. The red cell velocity in arterioles showed regular pulsatile waveforms synchronous with the systemic arterial pressure measured in the femoral artery. The amplitude of velocity pulsation was defined as the half of the difference between the maximum and minimum of the ensemble average vel … More ocity using the systemic pressure as a timing signal. The amplitude of velocity pulsation in the pial arterioles was 24 (]SY.+-。[) 9%, 29 (]SY.+-。[) 9% and 40 (]SY.+-。[) 11% at ICP = 5,30 and 50 mmHg, respectively. It increased gradually with ICP on the average. In individual arterioles, however, the amplitude of velocity pulsation showed a sharp increase at a certain critical value of ICP.The critical ICP ranged between 25 and 40 mmHg, increased with increasing vessel diameter and decreased from upstream to downstream along arteriolar trees. Theoretical calculations wereconducted based on a model assuming that the elastic modulus of arteriolar wall is a step function of transmural pressure and the network architecture is approximated by a porous tapered elastic tube. They suggest that the critical ICP corresponds to the internal pressure of the arteriole.Constant shear stress hypothesis has been introduced to explain the cubic dependence of the volumetric flow in arterioles on vessel diameter. The mechanism of the hypothesis is based on the flow dependent vasodilation mediated by nitric oxide (NO). However, our measurements by the FLDAM revealed that the flow rate in the rat pial arterioles is proportional to the 3.46 (]SY.+-。[) 0.18<@D2-@>D2th power of the diameter, which is significantly different from 3. To investigate the effects of NO on the velocity distribution, the red cell velocity was measured in the pial arterioles with diameter between 20 and 60 mum under the infusion of sodium nitoprusside (SNP,a potent NO donor). Both diamete and mean velocity increased by 14% on the average. The distributions of mean velocity and wall shear rate did not show significant changes compared to the control condition. Less

本研究利用自行研制的光纤激光多普勒血流显微镜（FLDAM）对不同病理状态下的血流动力学进行了分析。特别是，研究了颅内压升高对脉搏波沿软脑膜微动脉网沿着传播的影响以及一氧化氮对软脑膜微血管流速分布的影响。用FLDAM测量软脑膜微血管内红细胞流速，观察窗内压在0 ~ 50 mmHg之间的变化。小动脉红细胞流速呈规则的脉动波形，与股动脉的体循环动脉压同步。速度脉动幅度定义为系综平均速度最大值与最小值之差的一半 ...更多信息 速度使用系统压力作为定时信号。软膜小动脉的速度脉动幅度为24（±）SY。9%，29（）SY ±。[）9%和40（]SY.+-. ICP = 5、30和50 mmHg时，分别为11%。随着ICP的平均值的增加，它逐渐增加。但在个别小动脉中，当颅内压达到某一临界值时，流速脉动幅度急剧增大，临界颅内压在25 ~ 40 mmHg之间，随血管直径的增大而增大，沿沿着小动脉树由上游向下游逐渐减小。理论计算是基于一个模型，假设动脉壁的弹性模量是跨壁压的阶跃函数，网络结构近似为多孔锥形弹性管。提出了临界ICP与微动脉内压相对应的观点，并引入常切应力假说来解释微动脉内体积流量与血管直径的立方关系。该假说的机制是基于一氧化氮（NO）介导的血流依赖性血管舒张。然而，我们通过FLDAM进行的测量显示，大鼠软脑膜小动脉中的流速与3.46（]SY.+-. [）0.18<@D2-@>直径的D2次幂，与3有显著差异。为了研究NO对速度分布的影响，在输注硝普钠（SNP，一种有效的NO供体）的情况下，测量了直径在20和60 μ m之间的软脑膜小动脉中的红细胞速度。平均直径和平均流速均增加14%。平均速度和壁面剪切率的分布与对照组相比没有明显变化。少

项目成果

Seki, J., Sasaki, Y., Oyama, T., Yamamoto, J.: "Blood Flow Pulsation in the Brain Pial Microvessels in Rats Measured by Fiber-Optic LDA Microscope" Laser Anemometry - Advances and Applications. GALA e.V., Karlsruhe. 645-651 (1997)

Seki, J.、Sasaki, Y.、Oyama, T.、Yamamoto, J.：“通过光纤 LDA 显微镜测量大鼠脑软膜微血管中的血流脉动”激光风速测量 - 进展和应用。

Yamamoto, J., Seki, J., et al.: "The Differential Involvement of von Willebrand Factor,Fibrinogen,and Fibronectin in Acute Experimental Thrombosis in Rat Cerebral and Mesenteric Microvessels." Jpn.J.Physiol.47(5). 431-441 (1997)

Yamamoto, J.、Seki, J. 等人：“血管性血友病因子、纤维蛋白原和纤连蛋白在大鼠脑和肠系膜微血管急性实验性血栓形成中的差异参与”。

Sasaki, Y., Seki, J., Giddings, J.C., and Yamamoto, J.: "Effects of NO-Donors on Thrombus Formation and Microcirculation in Cerebral Vesseil of the Rat" Thrombosis and Haemostasis. 76 (1). 111-117 (1996)

Sasaki, Y.、Seki, J.、Giddings, J.C. 和 Yamamoto, J.：“NO 供体对大鼠脑血管中血栓形成和微循环的影响”血栓形成和止血。

Seki,J.,Sasaki,Y.,Oyama,T.& Yamamoto,J.: "Fiber-Optic Laser-Doppler Anemometer Microscope Applied to the Cerebral Microcirculation in Rats" Biorheology. 33. 463-470 (1996)

关 J.、佐佐木 Y.、小山 T.

Seki, J., Sasaki, Y., Ovama, T., Yamamoto J.: "Effects of Iatracranial Pressure on the Blood Flow Pulsation in the Rat Pial Microvessels" The Frontiers in Microcirculation Research. 185-191 (1997)

Seki, J.、Sasaki, Y.、Ovama, T.、Yamamoto J.：“颅内压对大鼠软脑膜微血管血流脉动的影响”微循环研究前沿。