Early manifestations of vitamin D effects in rat osteogenic sarcoma cells |
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Authors: | Kim Yee S. Birge Stanley J. Avioli Louis V. Miller Ruth |
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Affiliation: | (1) Department of Pharmacology, St. Louis University School of Medicine, 63104 St. Louis, Missouri, USA;(2) Division of Bone and Mineral Metabolism, The Jewish Hospital, 63110 St. Louis, Missouri, USA;(3) Washington University School of Medicine, 63110 St. Louis, Missouri, USA |
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Abstract: | Summary We have recently demonstrated that 48 hour exposure of ROS 17/2 cells to low concentrations of 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) (1.0 pg/ml) stimulated the cellular accumulation of45Ca, and exposure to high concentrations (160 pg/ml) inhibited such accumulation. In the present study, short-term (15 min) effects of the sterol on45Ca accumulation in ROS 17/2 cells were compared with the long-term (48 hours) effects in order to clarify mechanisms responsible for 1,25(OH)2D3 control of calcium metabolisms in ROS 17/2 cells. ROS 17/2 cells were grown for 48 hours in the presence and absence of 1,25(OH)2D3 and then incubated for an additional 15 min in the presence and absence of 1,25(OH)2D3 immediately before measuring45Ca accumulation. Cellular45Ca was measured after incubating the cells in the medium containing 0.5 μCi/ml of45CaCl2 for 4 min at 25°C. The effect of actinomycin D was determined by preincubating the cells in 0.1 μg/ml of actinomycin D for 45 min at 25°C. Exposure to low concentrations (1.0 pg/ml) of 1,25(OH)2D3 for either 48 hours or 15 min increased45Ca in the cells by 10–20%. An additional 15 min exposure following 48 hour exposure yielded an increase in the cellular45Ca similar to that after 48 hours or 15 min exposure. Exposure to high concentrations (160 pg/ml) for either 48 hour or 15 min decreased cell45Ca by approximately 20%.An additional 15 min exposure to the high concentrations did not change the 48 hour effect. Actinomycin D reversed early inhibitory effects of high concentrations, but had no effect on the early stimulatory effects of low concentrations. These results suggest that the mechanisms underlying the 15 min and 48 hour effects of 1,25(OH)2D3 are the same. Moreover, the mechanism responsible for the inhibitory effect of high concentrations is dependent onde novo protein synthesis whereas that for the stimulatory effects of low concentrations is not. |
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Keywords: | ROS 17/2 cells 1,25(OH)2D3 Early effects Calcium |
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