The Role of Calcium Flux and Its Relationship to Vitamin D Response in an IN VITRO Model of Chondrogenesis
Abstract
It is well established that Vitamin D metabolites affect proliferation, differentiation and maturation of cartilage cells. Previous studies have shown that growth zone chondrocytes respond primarily to 1,25- Dihydroxy Vitamin D3 whereas resting zone chondrocytes respond primarily to 24, 25-(OH)2D3. This study used the ionophore, A23187, to examine the hypothesis that the effects of vitamin D on cartilage cells are mediated by changes in calcium flux. Confluent, fourth passage cultures of growth zone and resting zone chondrocytes from the costochondral cartilage of 125 gram rats were used as the model system since these cells retain their differential response to the vitamin D metabolites. To examine whether calcium content might play a role in the mechanism of hormone action, cells were incubated with A23187 for 3, 6, 12, 15 or 30 minutes. Alkaline phosphatase (ALPase) and phospholipase A2 (PA2) are two enzymes shown previously to be regulated by 1,25-(OH)2D3 and 24,25-(OH)2D3. The specific activity of these enzymes was measured in the cell layer and in isolated plasma membranes and matrix vesicles. To determine whether the effect of ionophore was comparable to that of the vitamin D metabolites, this study also compared the effects of 1,25-(OH)2D3 and 24,25-(OH)2D3. (kt)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1990
- Accession Number
- ADA221207
Entities
People
- Gregory G. Langston
Organizations
- Air Force Institute of Technology