Resnick Andrew, Hopfer Ulrich
Department of Physiology and Biophysics, Case Western Reserve School of Medicine, Cleveland, Ohio 44106, USA.
Biophys J. 2007 Aug 15;93(4):1380-90. doi: 10.1529/biophysj.107.105007. Epub 2007 May 25.
Considerable experimental evidence indicates that the primary, nonmotile cilium is a mechanosensory organelle in several epithelial cell types. As the relationship between cellular responses and nature and magnitude of applied forces is not well understood, we have investigated the effects of exposure of monolayers of renal collecting duct chief cells to orbital shaking and quantified the forces incident on cilia. An exposure of 24 h of these cells to orbital shaking resulted in a decrease of amiloride-sensitive sodium current by approximately 60% and ciliary length by approximately 30%. The sensitivity of the sodium current to shaking was dependent on intact cilia. The drag force on cilia due to induced fluid flow during orbital shaking was estimated at maximally 5.2x10(-3) pN at 2 Hz, approximately 4 times that of thermal noise. The major structural feature of cilia contributing to their sensitivity appears to be ciliary length. As more than half of the total drag force is exerted on the ciliary cap, one function of the slender stalk may be to expose the cap to greater drag force. Regardless, the findings indicate that the cilium is a mechanosensory organelle with a sensitivity much lower than previously recognized.
大量实验证据表明，在几种上皮细胞类型中，初级不动纤毛是一种机械感觉细胞器。由于细胞反应与施加力的性质和大小之间的关系尚未完全了解，我们研究了将肾集合管主细胞单层暴露于轨道摇动的影响，并对作用于纤毛的力进行了量化。将这些细胞暴露于轨道摇动24小时导致amiloride敏感钠电流降低约60%，纤毛长度降低约30%。钠电流对摇动的敏感性取决于完整的纤毛。在2Hz时，轨道摇动期间诱导的流体流动对纤毛产生的阻力估计最大为5.2×10(-3)pN，约为热噪声的4倍。纤毛长度似乎是导致其敏感性的主要结构特征。由于总阻力的一半以上作用于纤毛帽，细长的纤毛柄的一个功能可能是使纤毛帽暴露于更大的阻力。无论如何，这些发现表明纤毛是一种机械感觉细胞器，其敏感性远低于先前的认识。
