Microcirculatory hemodynamic changes in cererbral microvascular occusion

在猫和大鼠软脑膜微循环活体显微镜观察的基础上，研究了脑微血管闭塞时脑微循环血流动力学的变化。动物用戊巴比妥钠麻醉，机械通气。开颅手术后，准备一扇关闭的颅窗。我们使用荧光视频显微镜系统对大脑皮层表面的微循环进行了直接观察。FITC标记的红细胞和RITC(罗丹明B)标记的葡聚糖分别用于显示微血管和血流。将FITC标记的乳胶微粒(直径约40微米)注入颈总动脉作为微栓子模型。在RITC视频图像的基础上，测量了软脑膜微血管的内径、长度和网络结构。基于FITC视频图像，我们使用双窗技术测量了红细胞的速度。通过扫描大脑皮质表面的一块区域，我们重建了微血管的网络结构。本文的荧光影像显示：1)大脑皮质微血管(小动脉和小静脉)呈小动脉-小动脉吻合的连通结构；2)小动脉弓提供了一条多途径的血流通道。由于微动脉拱门就像一个连接主干的旋转器，当微球堵塞单个小动脉时，血液流动从未停止过。在微栓子导致微血管闭塞的情况下，Dypath血流回路可能会在脑微血管网络中持续流动血液。

Cerebral microcirculatory hemodynamic changes were investigated during cerebral microvascular occlusion, based on an intravital microscopic observation of the pial microcirculation in cat and rats. The animals were anesthetized with pentobarbital sodium and mechanical ventilated. After craniotomy, a closed cranial window was prepared. We made a direct observation of the microcirculation on the cerebrocortical surface using a fluorescence videomicroscopic system. FITC-labeled red cells and RITC (Rhodamine-B) labeled dextran were used for visualzing microvessels and blood flow, respectively. As a model of microemboli, latex microsheres (diameter : around 40 mum), which were labeled with FITC,were injected into a common carotid artery. Based on RITC video-image, we measured internal diameter, length and network structure, of pial microvessels. Based on FITC videoimage, we measured red cell velocity, using a dual window technique. By scanning over an area of the cerebrocortical surface, we reconstructed the network structure of microvessels. The present fkuorescence videoimage showed that i) cerebrocortical microvessels (arterioles and venules) show an acrcading structure with arteriole-arteriole anastomoses ; ii) the arteriolar arcade proivides a multiple pathway for blood flow. Since the arteriolar arcade was like a rotary to connect main streams, blood flow was never stopped when a single arteriole was occluded with microspheres. Under microvascular occlusion due to microemboli, dypath flow-circuits may work to flow blood continuously in the cerebral microvascular network.