Failure of 1,25 Dihydroxycholecalciferol [1,25-(OH)₁-D₃] to Modify Cyclic AMP Levels in Parathyroid Hormone-Treated and Untreated Bone Cells (1)

Abstract

Treatment with 1,25-(OH)2-D₃ (1 ng/ml - 25 ng/ml) for periods ranging from 2.5 min. to 60 min. did not alter cyclic AMP levels in bone cells isolated from periosteum-free rat calvaria, or in cells isolated from rat periosteal tissues. 1,25-(OH)2-D₃ failed to modify the acute increases in cyclic AMP elicited by PTH (10 ng/ml -1 ug/ml). Two separate 1,25-(OH)₂-D₃ preparations, biologically active in other systems, were ineffective under a wide variety of experimental conditions. These results suggest that 1,25-(OH)₂-D₃ is not an acute modulator of cyclic AMP metabolism in PTH-treated and untreated bone cells.