Abstract
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.
Original language | English |
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Pages (from-to) | 125-32 |
Number of pages | 8 |
Journal | Calcified Tissue International |
Volume | 54 |
Issue number | 2 |
Publication status | Published - Feb 1994 |
Keywords
- 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