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标题：In vitro metabolism of 25-hydroxyvitamin D3 by isolated rat kidney cells
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作者：Russell T. Turner ; Brian L. Bottemiller ; Guy A. Howard 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1980
卷号：77
期号：3
页码：1537-1540
DOI：10.1073/pnas.77.3.1537
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Cells were dispersed from rat kidney after enzymatic digestion of the extracellular matrix. When the cells were suspended in a serum-free medium and incubated with 3H-labeled 25-hydroxyvitamin D3 (25-OH-D3) several polar metabolites, including 1,25-(OH)2[3H]D3 and 24,25-(OH)2[3H]D3 were produced. The specific activities of the 25-OH-D3:1- and 24-hydroxylases in isolated rat kidney cells were 10-100 times greater than in avian kidney homogenates. The rates of production of 1,25-(OH)2D3 and 24,25-(OH)2D3 were linear over a wide range in cell densities (0.65-5.0 x 106 cells per ml) and substrate concentrations (3.5-70 nM). The rate of production of 24,25-(OH)2[3H]D3 from 25-OH-[3H]D3 by cells isolated from rats fed control diet was linear with time for up to 30 min, while the synthesis of 1,25-(OH)2[3H]D3 was linear for over 90 min. The specific activity of the 25-OH-D3:1-hydroxylase was increased in kidney cells from vitamin D-deficient rats (11.5 fmol/min per 106 cells) as well as calcium-deficient rats (8.1 fmol/min per 106 cells) when compared to cells from rats fed the control diet (2.0 fmol/min per 106 cells). Also, the specific activity of the 25-OH-D3:24-hydroxylase was reduced in cells from the vitamin D-deficient rats (<0.2 fmol/min per 106 cells) and calcium-deficient rats (5.1 fmol/min per 106 cells) compared to the controls (15.2 fmol/min per 106 cells). On the basis of these results, as well as previous in vivo studies, we conclude that the metabolism of 25-OH-D3 by freshly isolated rat kidney cells reflects the in vivo activities of the renal vitamin D-metabolizing enzymes and may prove useful as an assay.
关键词：1,25-dihydroxyvitamin D₃ ; 24,25-dihydroxyvitamin D₃ ; vitamin D deficiency ; calcium deficiency