FUNCTIONAL STUDIES OF OSTEOBLASTS

这项建议是对我们早些时候的组织化学发现的回应 提示成骨细胞具有高活性的质膜钙离子。 ATPase在关节尖端和外侧(非骨侧)的移位 手机。因为这种酶的作用是外向的钙 在已经研究过的所有其他细胞中的易位，这是预期的 成骨细胞中的Ca-ATPase也会将钙移出细胞。 Ca-ATPase的ATP水解性及其Ca~(++)的转运 成骨细胞的特性及其刺激物质的调节 将在由质膜制备的囊泡中进行检查 成骨细胞。此外，还证明了Na/Ca的存在 将寻找交换剂和钙离子通道。据推测， CA-ATPase存在于成骨细胞的顶侧， Na/Ca交换器可能存在于细胞的基面。两个来源 将利用成骨细胞：(1)新生大鼠来源的成骨细胞 代表膜内骨形成的头盖骨，因此， 头面部骨骼；和(2)禽髓骨的小梁骨， 高度新陈代谢活跃的骨骼，它代表来自 软骨内骨化过程。这些研究的目的是提供 洞察成骨细胞功能的机制，细胞是重要的 在颅面发育、骨科和了解疾病方面 已经注意到骨形成减少的骨丢失。

This proposal is in response to our earlier histochemical finding that suggests that osteoblasts possess a highly active plasma membrane Ca++- translocating ATPase on the apicial and lateral (non-bone) sides of the cell. Since the role of this enzyme is outwardly-directed calcium translocation in all other cells that have been studied, it is expected that the Ca-ATPase in osteoblasts will also move calcium out of the cell. The ATP-hydrolyzing capacity of the Ca-ATPase, its Ca++ translocating properties and its regulation by substances known to stimulate osteoblasts will be examined in vesicles prepared from the plasma membrane of osteoblasts. In addition, demonstration of the existence of a Na/Ca exchanger and calcium channels will be sought. It is postulated that the Ca-ATPase exists on the apico-lateral sides of the osteoblast and that a Na/Ca exchanger may be present on the basal side of the cell. Two sources of osteoblasts will be utilized: (1) osteoblasts derived from neonate rat calvaria which represent intramembranous bone formation and, hence, the cranio-facial skeleton; and (2) trabecular bone of avian medullary bone, a highly metabolically active bone, which represents bone derived from the endochondral ossification process. The studies are intended to provide insight into mechanisms of osteoblast function, cells which are important in cranio-facial development, orthopedics and understanding diseases of bone loss in which decreased bone formation has been noted.