Comparative studies on the 25-hydroxylation of vitamin D 3 and dihydrotachysterol 3 .
Comparative studies on the 25-hydroxylation of vitamin D 3 and dihydrotachysterol 3 .
复制标题
维生素D 3 和二氢速甾醇3 25-羟基化的比较研究。
DOI：
10.1016/s0021-9258(19)43996-3
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发表时间：
1973
期刊：
影响因子：
--
通讯作者：
H. DeLuca
中科院分区：
文献类型：
--
作者：
M. Bhattacharyya;H. DeLuca
Liver homogenates hydroxylate dihydrotachysterol3in position 25 equally well whether they are prepared from rats low in vitamin D or from rats treated with vitamin D3. This contrasts with the liver homogenate 25-hydroxylation of vitamin D3which is markedly reduced by pretreatment with vitamin D3. In addition, the rate of appearance of 25-hydroxy[3H]dihydrotachysterol3in the blood following a dose of [3H]dihydrotachysterol3is not reduced by prior treatment with unlabeled vitamin D3or dihydrotachysterol in contrast to the effect of prior vitamin D3treatment onin vivovitamin D325-hydroxylation. Furthermore the rate of appearance of 25-hydroxyvitamin D3in the blood increases only about 2-fold with a 100-fold increase in vitamin D3dose, while the rate of appearance of 25-hydroxydihydrotachysterol3increases 100-fold with a 100-fold increase in dihydrotachysterol3dose. These results strongly suggest that the 25-hydroxylation of dihydrotachysterol is not regulatedin vivoas is the 25-hydroxylation of vitamin D3. They also support the idea that the regulation of calciferol-25-hydroxylase activity functions to maintain a low circulating level of 25-hydroxyvitamin D3in the blood even when large amounts of vitamin D3are being ingested.
