A MODEL FOR THE EXCITATION OF OSTEOCYTES BY MECHANICAL LOADING-INDUCED BONE FLUID SHEAR STRESSES
A MODEL FOR THE EXCITATION OF OSTEOCYTES BY MECHANICAL LOADING-INDUCED BONE FLUID SHEAR STRESSES
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DOI：
10.1016/0021-9290(94)90010-8
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发表时间：
1994-03-01
影响因子：
2.4
通讯作者：
ZENG, Y
中科院分区：
文献类型：
--
作者：
WEINBAUM, S;COWIN, SC;ZENG, Y
提出了一种新的实验可验证的假设，通过机械感觉转导机制，通过交流骨细胞感知骨钙化基质成分中非常小的体内菌株。我们认为，骨细胞虽然对大量的流体压力没有反应，但可以通过作用于骨细胞过程膜上的相对较小的流体剪切应力来刺激骨细胞。Blot的多孔介质理论用于将整个骨的轴向和弯曲载荷与骨小管中骨细胞过程的流动联系起来。在这个理论中，我们感兴趣的骨孔是小管中围绕着骨细胞突起的充满蛋白聚糖的液体环。我们发现，先前预测的流体孔隙压力弛豫时间对于腔隙-管状孔隙度来说短了100倍，因为他们忽略了与骨细胞表面膜上的蛋白聚糖基质及其细胞过程相关的流体阻力。最近的理论发展在Tsay和Weinbaum [J]。流体力学。226,125-148(1991)]通过交联纤维填充通道的流动被用来模拟通过这种蛋白聚糖基质的流动。预测的孔隙松弛时间为1 ~ 2 s，与Salzstein和Pollack测量的时间非常接近[J]。生物力学20,271-280(1987)]。此外，使用该模型，预测的流体诱导剪切应力的大小为8-30 dyn cm(-2)，与在成骨细胞和其他细胞中测量的流体剪切应力相似，其中观察到细胞内Ca2+剪切应力响应。该模型还与解剖数据和孔隙流体压力松弛时间数据相结合，表明纤维之间的间距约为7 nm。根据Michel [J.]的模型，该结果与小管孔空间充满由白蛋白排序的葡萄糖氨基聚糖的观点是一致的。[j].中国生物医学工程学报，2004,27(5):387 - 387。新的假设也被证明与McLeod等人的实验相一致。生物力学[已提交]表明高频低振幅的体位应变可以维持甚至增加骨量。
A new experimentally testable hypothesis is advanced for the mechanosensory transduction mechanism by which communicating osteocytes sense the very small in vivo strains in the calcified matrix components of bone. We propose that the osteocytes, although not responsive to substantial fluid pressures, can be stimulated by relatively small fluid shear stresses acting on the membranes of their osteocytic processes. Blot's porous media theory is used to relate the combined axial and bending loads applied to a whole bone to the flow past the osteocytic processes in their canaliculi. In this theory, the bone pores of interest ale the proteoglycan filled fluid annuli that surround the osteocytic processes in the canaliculi. We show that previously predicted fluid pore pressure relaxation times were a hundred-fold too short for the lacunar-canalicular porosity because they neglected the fluid drag associated with proteoglycan matrix on the surface membrane of the osteocyte and its cell processes. The recent theory developed in Tsay and Weinbaum [J. Fluid Mech. 226, 125-148 (1991)] for flow through cross-linked fiber filled channels is used to model the flow through this proteoglycan matrix. The predicted pore relaxation time, 1-2 s, closely corresponds to the times measured by Salzstein and Pollack [J. Biomechanics 20, 271-280 (1987)]. Furthermore, using this model, the magnitude of the predicted fluid induced shear stresses, 8-30 dyn cm(-2), is shown to be similar to the fluid shear stresses measured in osteoblasts and other cells in which an intracellular Ca2+ shear stress response had been observed. This model is also used, in conjunction with anatomical data and the pore fluid pressure relaxation time data, to show that the spacing between the fibers is approximately 7 nm. The result is consistent with the notion that the canalicular pore space is filled with glucosaminoglycans that are ordered by albumin according to the model of Michel [J. Physiol. 404, 1-29 (1988)]. The new hypothesis is also shown to be consistent with the experiments of McLeod et al. [J. Biomechanics (submitted)] which suggest that high-frequency low-amplitude postural strains can maintain and even increase bone mass.