FUNCTIONAL STUDIES OF OSTEOBLASTS

这一建议是对我们早期组织化学发现的回应， 表明成骨细胞具有高度活性的质膜Ca ++- 易位ATP酶的顶侧和侧（非骨）侧， cell. 由于这种酶的作用是向外定向钙 易位在所有其他细胞已被研究，预计 成骨细胞中的钙ATP酶也会将钙移出细胞。 Ca-ATP酶的ATP水解能力、Ca~（++）转运能力、 已知刺激成骨细胞的物质的性质及其调节 将在从质膜制备的囊泡中检查 成骨细胞 此外，证明存在Na/Ca 交换器和钙通道。 据推测， Ca-ATPase存在于成骨细胞的顶外侧， Na/Ca交换剂可以存在于细胞的基底侧。 两个来源 本实验将利用的成骨细胞有：（1）新生大鼠成骨细胞 颅骨代表膜内骨形成，因此， 颅面骨骼;（2）鸟类骨髓骨的骨小梁， 高代谢活性骨，其代表源自 软骨内骨化过程 这些研究旨在提供 深入了解成骨细胞功能的机制， 在颅面发育、整形外科和理解 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.