Turner C H, Owan I, Takano Y
Department of Orthopedic Surgery, Indiana University Medical Center, Indianapolis 46202, USA.
Am J Physiol. 1995 Sep;269(3 Pt 1):E438-42. doi: 10.1152/ajpendo.1995.269.3.E438.
Bone tissue can detect and respond to its mechanical environment, but there is no consensus for how bone cells detect mechanical loads. Some think that cells sense tissue deformation (strain) and respond when strain is abnormally high. However, strains in bone tissue are usually very small, and it is questionable whether bone cells are sensitive enough to detect them. Another theory suggests that mechanical loads are coupled to the bone cells by stress-generated fluid flow within the bone tissue, which is dependent on the rate of change of bone strain. We applied bending loads to the tibiae of adult rats to create equivalent peak strains in the bone tissue but with varied rates of strain. Bone formation was significantly increased in the two experimental groups when the highest strain rates were compared with lower strain rates (P < 0.01), and the amount of new bone formation was directly proportional to the rate of strain in the bone tissue. These results suggest that relatively large strains alone are not sufficient to activate bone cells. High strain rates and possibly stress-generated fluid flow are required to stimulate new bone formation.
骨组织能够检测并对其力学环境作出反应，但对于骨细胞如何检测机械负荷尚无定论。一些人认为细胞感知组织变形（应变），并在应变异常高时作出反应。然而，骨组织中的应变通常非常小，骨细胞是否足够敏感以检测到它们值得怀疑。另一种理论认为，机械负荷通过骨组织内应力产生的流体流动与骨细胞耦合，这取决于骨应变的变化率。我们对成年大鼠的胫骨施加弯曲负荷，以在骨组织中产生等效的峰值应变，但应变率不同。当将最高应变率与较低应变率进行比较时，两个实验组的骨形成均显著增加（P < 0.01），并且新骨形成的量与骨组织中的应变率成正比。这些结果表明，仅相对较大的应变不足以激活骨细胞。需要高应变率以及可能的应力产生的流体流动来刺激新骨形成。
