Schwartz E A, Leonard M L, Bizios R, Bowser S S
Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA.
Am J Physiol. 1997 Jan;272(1 Pt 2):F132-8. doi: 10.1152/ajprenal.1997.272.1.F132.
Since a nonmotile, primary (9 + 0) cilium projects from most mammalian kidney epithelial cells into the tubule lumen, where it is exposed to fluid motion, the present study examined primary cilium response to fluid shear stress. The reversible, large-angle bending of the primary cilium upon exposure to fluid shear forces (10(-11)-10(-10) N.m2 = 10(-8)-10(-7) dyn/cm) was characterized in vitro using videomicroscopic side views of PtK1 cells, and the cilium was then mathematically modeled as a cantilevered beam. The flexural rigidity of the primary cilium was calculated to be 3.1 +/- 0.8 x 10(-23) N.m2 with a corrected quadruple integration approach and 1.4-1.6 x 10(-23) N.m2 with the "heavy elastica" theory. Comparison of theoretical profiles to the experimental bending responses of cilia established the validity of the "heavy elastica" model; this model, in turn, was used to predict primary cilium bending behavior under representative conditions in the rat nephron. The results of the study are consistent with the hypothesis that primary cilia serve a mechanosensory function in kidney epithelial cells.
由于大多数哺乳动物肾上皮细胞会伸出一根无运动能力的初级（9 + 0）纤毛进入肾小管腔，使其暴露于液体流动中，因此本研究检测了初级纤毛对流体剪切力的反应。使用PtK1细胞的视频显微镜侧视图在体外对初级纤毛暴露于流体剪切力（10（-11）-10（-10）N·m2 = 10（-8）-10（-7）dyn/cm）时的可逆、大角度弯曲进行了表征，然后将纤毛数学建模为悬臂梁。采用修正的四重积分法计算得出初级纤毛的弯曲刚度为3.1 ± 0.8 × 10（-23）N·m2，采用“重弹性曲线”理论计算得出为1.4 - 1.6 × 10（-23）N·m2。将理论曲线与纤毛的实验弯曲反应进行比较，证实了“重弹性曲线”模型的有效性；该模型进而被用于预测大鼠肾单位代表性条件下初级纤毛的弯曲行为。研究结果与初级纤毛在肾上皮细胞中发挥机械传感功能这一假说相符。
