Molecular Biological and Bio-Engineering Study of Blood Flow-Sensing and Responding Mechanism of Vascular Endothelial Cells.

血流的血流动力被认为调节内皮细胞的功能，并在调节血管结构和启动动脉粥样硬化的早期病变中发挥重要作用。为了证明这一假设，我们研究了血管内皮细胞如何识别血流中的血流动力学变化并调节其功能。利用自行设计的流体力学加载装置，对培养的血管内皮细胞施加流体作用，研究其胞浆内游离钙离子浓度、内皮细胞再生能力、DNA合成、胶原合成和分泌及血管内皮细胞衍生的松弛因子(EDRF)的变化。结果如下：1)向内皮细胞施加介质流可引起细胞内钙离子浓度的一过性升高。血流诱导的钙反应需要在灌流液中存在三磷酸腺苷，特别是在500nM三磷酸腺苷时，End…更多的内皮细胞表现出随着流量的逐渐增加而逐渐增加的钙浓度(剪应力从0到42dyn/cm^2)，这表明内皮细胞通过第二信使钙离子将流量(剪应力)感知为刺激。2)施加1~3dyn/cm~2的流动屈服切应力24~48小时，可刺激机械剥脱后再生的内皮细胞迁移和增殖。细胞迁移主要发生在下游。Flow应用还促进了再生过程中内皮细胞的DNA合成，并增加了处于细胞周期有丝分裂阶段的细胞的百分比。此外，内皮细胞对FLOW产生反应，产生平滑肌细胞迁移的刺激物。血管内皮细胞产生细胞外基质胶原蛋白和EDRF，EDRF可以松弛平滑肌细胞，抑制血小板聚集，这些功能可以通过流动应用来刺激。我们还观察到，内皮细胞由流动诱导的EDRF释放与流动诱导的钙瞬变有关。较少

The hemodynamic force of blood flow is speculated to modulate endothelial cell functions and play an important role in the regulation of the structure of the vessel and in the initiation of early lesions of atherosclerosis. To prove this hypothesis, we studied how vascular endothelial cells recognize the hemodynamic changes in blood flow and modulate their functions. By using a flow-loading apparatus hydrodynamically designed in our laboratory, we applied fluid flow to cultured vascular endothelial cells, and studied the changes in cytoplasmic free calcium ion concentrations, ability of endothelial regeneration, DNA synthesis, production and secretion of collagen, and release of endothelium-derived relaxing factor (EDRF). The results obtained were as follows : 1) Application of medium flow to endothelial cells induced a transient rise in cytoplasmic calcium concentrations. The flow-inducedcalcium response needed the presence of ATP in perfusion fluids and, especially at 500 nM ATP, end … More othelial cells showed the gradual increase in calcium concentrations in response to the gradual increase in flow (shear stress ranging from 0 to 42 dyn/cm^2), indicating that endothelial cells perceive flow (shear stress) as a stimulus via a second messenger, calcium ion. 2) Application of flow yielding shear stress of 1-3 dyn/cm^2 for 24-48 hours stimulated endothelial cell migration and proliferation during regeneration after mechanical denudation. Cell migration occurred downstream prominently. Flow application also enhanced DNA synthesis by endothelial cells during regeneration and increased the percentage of the cells locating in the mitotic phase of the cell cycle. Furthermore, endothelial cells reacted to flow to produce stimulators of smooth muscle cell migration. Endotial cells produce collagen, an extracellular matrix, and EDRF which relaxes smooth muscle cells and inhibits platelets aggregation, and these functions were stimulated by flow application. It was also observed that the flow-induced release of EDRF by endothelial cells relate to the flow-induced calcium transients. Less