[Influence of epiphyseal cartilages on bone resorption of fetal rat femora].
We developed a facile method for studying bone resorption using fetal rat femur by labelling the bone with 45Ca in vitro. We found that cartilages stimulated the bone resorption of a shaft which was obtained by cutting off both distal and proximal cartilages from the femur. When the shaft was co-cultured with the cartilages isolated by a 0.4-microns microporous membrane in the same Transwell, the bone resorption of the shaft was increased. This finding suggests that the stimulation of bone resorption by the cartilages is not a result of recruitment of osteoclasts or the precursor cells from the cartilages. Indomethacin (10(-6) M) failed to influence the bone resorbing activity of the cartilages. The bone resorbing activity in the supernatant obtained from the cartilage-culture was decreased by heating. The bone resorbing activity of the supernatant did not remain in the lipid-extract or the pronase-digested supernatant, but was present in a fraction whose molecular weight was greater than 50,000. These results collectively suggest that the cartilages produce a bone resorption-stimulating factor(s) which is water-soluble, is a non-prostanoid material, contains protein and has a molecular weight greater than 50,000.
Tsutsumi
N
N
Central Research Laboratories, Kissei Pharmaceutical Co., Ltd., Nagano, Japan.
Nagata
H
H
Tsuyuki
J
J
Ujiie
A
A
D000818:Animals; D001862:Bone Resorption / Q000378:metabolism*; D002356:Cartilage / Q000378:metabolism / Q000502:physiology*; D046508:Culture Techniques; D005260:Female; D005269:Femur / Q000187:drug effects; D005333:Fetus; D051381:Rats; D017208:Rats, Wistar