剪应力对培养内皮细胞表面ATP浓度的调节

剪应力信号转导是目前细胞生物力学的研究热点之一。Ca^2＋作为一种第二信使在剪应力信号转导中扮演了重要角色，钙信号转导是通过胞内自由Ca^2＋浓度变化来实现的。胞内Ca^2＋浓度的大小不仅依赖于细胞承受剪应力的大小，同时依赖于细胞外ATP的浓度。本文采用剪应力诱发内皮细胞分泌ATP的时变模型，通过对平行平板流动腔中的ATP浓度场进行数值模拟，分析了剪应力对培养内皮细胞表面ATP浓度的影响。结果表明，剪应力诱发的ATP分泌明显影响细胞表面附近ATP的浓度；剪应力、对流和扩散效应、ATP的水解作用共同决定了细胞外表面附近ATP的浓度。这一结果提示，剪应力大小并非剪应力信号转导过程中的唯一决定因素；剪应力的作用、激动剂的浓度改变共同参与了剪应力信号转导。

Shear Stress Modulation of ATP Concentration at Cultured Endothelial Cells Surface

As a second messenger, the cytosolic free calcium plays an important role in mechano-transduction which has been a highlight in cell biomechanics. Calcium signaling is determined by changes in the intracellular free calcium concentration. The intracellular free calcium concentration is mediated not only by fluid shear stress but also by extracellular ATP concentration. The effect of shear stress on the ATP concentration at the endothelial surface was analyzed by use of numerical modeling of ATP concentration fields in a parallel-plate flow chamber based on a time-dependent model for shear stress induced ATP release from endothelial cells. The results demonstrate that shear stress induced ATP release obviously affects the ATP concentration at the endothelial surface; shear stress, convection and diffusion, ATP hydrolysis synergistically determine the ATP concentration at the endothelial surface. It is also demonstrated that the effects of shear stress and the concentration of agonist synergistically participate in shear stress signal transduction; shear stress is not an exclusive factor,