Heterogeneity of bone resorbing factors produced by unstimulated murine osteoblasts in vitro and in response to stimulation by parathyroid hormone and mononuclear cell factors.
The bone resorbing activity of factors released from monolayer cultures of osteoblasts (OB) was examined by measurement of calcium released by neonatal mouse calvaria in vitro. Unstimulated conditioned media (CM) were found to contain significant bone resorbing activity, which was partially inhibited by indomethacin, dexamethasone and nordihydroguaiaretic acid. Ultrafiltration of CM (molecular weight cut-off of 5000) revealed bone resorbing activity in the filtrate and retentate. Fractionation of the CM by high-performance liquid chromatography revealed four major peaks of bone resorbing activity. Stimulation of the OB by mononuclear cell factor and parathyroid hormone significantly increased the synthesis and/or release of these factors with a relatively greater increase of lipid-soluble, low molecular-weight activity. These results suggested an important role for relatively small non-popular mediators in hormonally stimulated bone resorption.
Meghji
S
S
Joint Department of Oral and Maxillofacial Surgery, Institute of Dental Surgery, London, England.
Sandy
J R
JR
Scutt
A M
AM
Harvey
W
W
Harris
M
M
D000818:Animals; D001685:Biological Factors / Q000302:isolation & purification* / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D016207:Cytokines; D006168:Guinea Pigs; D008970:Molecular Weight; D015846:Monokines; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000494:pharmacology*; D012886:Skull
D001685:Biological Factors; D016207:Cytokines; D015846:Monokines; D010281:Parathyroid Hormone; C025940:bone resorption factor; D002118:Calcium