Induction of a low voltage-activated, fast-inactivating Ca2+ channel in cultured bone marrow stromal cells by dexamethasone
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Colleges, School and Institutes
The production of biochemical markers associated with the osteoblastic phenotype, and accompanying changes in the expression of voltage-operated Ca2+ channels, have been examined in rat bone marrow stromal cell cultures treated with dexamethasone (10(-8) M). Whole cell clamp analysis of voltage-operated Ca2+ channels in control cultures (using Ba2+ as the charge carrier) revealed primarily a high voltage-activated (HVA), slowly inactivating current, which was enhanced two- to threefold by treatment of the cells with Bay K 8644 (300 nM) and inhibited by nifedipine (4 microM). In dexamethasone-treated cultures, the I-V relationship for inward current was shifted to more positive potentials in comparison with control cells. Most cells in these cultures possessed both the HVA current and also a faster inactivating, low-voltage-activated (LVA), nifedipine-resistant current. These two currents could be separated both by nifedipine and by the use of steady state inactivation of the LVA current. The two components of the Ba2+ current varied widely in their relative size. The combination of LVA and HVA currents seen in dex-induced stromal cells resembles records of voltage-operated Ca2+ channels from cultures of calvarial osteoblasts.
|Number of pages||8|
|Journal||Calcified Tissue International|
|Publication status||Published - Feb 1994|
- Dexamethasone, Animals, Alkaline Phosphatase, Electric Stimulation, Nifedipine, Collagen, Rats, Phenotype, Bone Marrow, Bone Marrow Cells, Calcium Channels, Osteoblasts, Cells, Cultured, Rats, Wistar, 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester, Male