Increased ATPase and Decreased Alkaline Phosphatase Activities by Parathyroid Hormone in Cultured Chick Embryo Tibiae 1

Summary

Addition of PTH to the medium of embryonic chick tibiae in organ culture caused a decrease in AP activity. Total ATP-ase activity was the same in control and treated bones, but ATPase activity assayed in the presence of levamisole, an inhibitor of bone AP activity, was greater in PTH-treated bones. These data suggest that there are at least two different phosphatase activities in bone with optimal activity at alkaline pH: a nonspecific alkaline phosphatase which is decreased in PTH-treated bones, and an ATPase which is increased by the hormone.