[Cartilage and vitamin D in vitro (author's transl)]

Interactions between cartilage and vitamin D metabolism were studied in vitro. Chondrocytes were isolated from rabbit growth plate cartilage and cultured. These cells are able to transform 25-hydroxycholecalciferol in 24, 25-dihydroxycholecalciferol. Metabolic transformation is modulated by 1, 25-dihydroxycholecalciferol but not by parathyroid hormone neither by extracellular calcium concentrations. 24, 25-(OH) 2D3 and 1, 25-(OH) 2D3 are active on the cellular metabolism of cultured chondrocytes in a different way : 24, 25-(OH) 2D3 stimulates the proteoglycan synthesis in "mature" chondrocytes 1, 25-(OH) 2D3 increases DNA polymerase activities in chondrocytes during the logarithmic phase of division. Finally, specific sites of nuclear receptors of 24, 25-(OH) 2D3 are present in chondrocytes.