THE PHYSIOLOGICAL RESPONSE OF OSTEOBLASTS TO A GRADIENTLY INCREASED STRETCHING
成骨细胞对梯度拉伸应变的响应

A four-point bending apparatus was used to apply a cyclic stretching to osteoblasts derived from Wistar calvaria. In order to investigate the responses of osteoblasts to the changing mechanical environment, a new loading method, the gradiently increasing stretching was also designed. The strain magnitude which cells were loaded was increased by 500 με every 2 h. The results showed that stretching at 500 με for 2~6 h increased the proliferation, ALP activity and extracellular calcium secretion of osteoblasts. On the contrary, stretching at 1000 με and 1500 με inhibited the proliferation, ALP activity and extracellular calcium secretion. When cells were stimulated by gradiently increased loading, the proliferation index, ALP activity and extracellular calcium synthesis decreased rapidly as the stimulation was changed from an optimal stretching (500 με) to an inhibitive stimulation (1000 με, 1500 με). The results suggested that osteoblasts can distinguish between different strain magnitudes and regulate their physiological functions to adapt to the changing mechanical environment.