Direct modulation of 25-hydroxyvitamin D3 hydroxylation in kidney tubules by 1,25-dihydroxyvitamin D3 |
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Authors: | J.L. Omdahl L.A. Hunsaker |
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Affiliation: | Department of Biochemistry School of Medicine University of New Mexico Albuquerque, New Mexico 87131 USA |
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Abstract: | Kidney tubules obtained from chicks fed a high-calcium low-phosphorus diet retained 25-hydroxyvitamin D3-1-hydroxylase activity after a 10 h incubation in serum-free minimum essential medium. Inclusion of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) in the medium prompted a suppression of 25-hydroxyvitamin D3-1-hydroxylase and the induction of 25-hydroxyvitamin D3-24-hydroxylase activities. The enzyme switch-over response could be prompted by 1.6 × 10?7 M 1,25-dihydroxyvitamin D3 and occurred within 6 h following treatment. Medium calcium appeared to augment the metabolite's switch-over action. |
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