应力方向对内皮细胞力学传递和功能的影响

剪切力可经由应力感受、信息传递和基因与蛋白质的表达来调控血管内皮细胞的功能。层流剪切力会导致单核细胞趋化蛋白质(MCP-1)及多种增生基因的迅速上调。但有特定方向的持久层流剪切力会使MCP-1及增生基因与蛋白下调, 同时并上调抑制内皮细胞增生的基因与蛋白。复杂的流型没有什么固定的方向，会使MCP-1及增生基因持续上调，因而增加单核细胞的侵入及内皮细胞的分裂及凋亡。在动脉的直管部分，层流剪切力有特定的方向，因此有抗动脉粥样硬化的作用。在动脉分支部位，复杂的流型有促使动脉粥样硬化的作用。所以，应力的方向对内皮细胞在正常及疾病时的功能有重要影响。

Role of Stress Direction on Mechanotransduction and Functions of Endothelial Cells

Shear stress can regulate vascular endothelial cell(EC)functions through membrane sensing,intracellular signal transduction,and modulation of gene and protein expressions.Laminar shear stress causes transient increases in the expressions of MCP-1 and the genes and proteins that upregrulate proliferation of ECs.The continued application of such shear flow with a definitive direction,however,causes the down-regulation of these molecules and the up-regulation of genes and proteins that inhibit growth.Complex flow pattern that does not have a definitive direction causes sustained increases of MCP-1 and the genes and proteins that stimulate proliferation,thus enhancing the invasion of monocytes and the turnover of ECs.In the straight part of the arterial tree,laminar flow prevails and has anti-atherogenic effects.In contrast,the disturbed flow at branch points does not have a specific direction and is atherogenic.Therefore,the directionality of shear stress plays an important role in regulation of EC functions in health and disease.