Parathyroid Hormone Stimulation of Collagenase Secretion by Isolated Bone Cells*

Cells isolated from fetal rat calvaria were cultured in a [14C]glycine-labeled collagen gel. This method of culture places the cells in an environment similar to that in the intact tissue and provides a means for assaying the release of collagenase from the cells. Degradation of the collagen matrix begins within the first 3 h of cell culture, the earliest time point at which samples were taken, and continues for at least 12 h. When cells were prepared from calvaria incubated for 30 min with parathyroid hormone (PTH), there was a marked decrease in the collagenase content of the freshly isolated cells, indicating that secretion of collagenase had been enhanced by PTH. Upon subsequent culture of control and PTH-pretreated cells, there was an increase in lysis of collagen gels surrounding the hormone-treated cells within 8 h. The increased collagenolysis was prevented by exposure of the cells to puromycin before and during culture, suggesting that collagenase synthesis also was stimulated by PTH.