title: Stimulation of 24,25-dihydroxyvitamin D3 production by 1,25-dihydroxyvitamin D3.
abstract: Vitamin D-deficient rats produce [(3)H]1,25-dihydroxyvitamin D(3) from [(3)H]25-hydroxyvitamin D(3) regardless of dietary content of calcium or phosphate. A daily dose of 130 picomoles of 1,25-dihydroxyvitamin D(3) for a period of 5 days reduces production of [(3)H]1,25-dihydroxyvitamin D(3) to essentially zero and stimulates production of [(3)H]24,25-dihydroxyvitamin D(3). A daily dose of 325 picomoles of 25-hydroxyvitamin D(3) has a similar but less dramatic effect. On the other hand, 650 picomoles daily of 24,25-dihydroxyvitamin D(3) given to vitamin D-deficient rats had no effect. Thus it appears that 1,25-dihydroxyvitamin D(3) is an important factor in the regulation of kidney metabolism of 25-hydroxyvitamin D(3).
mesh_terms: D000818:Animals; D002118:Calcium / Q000097:blood; D002136:Calcium, Dietary; D004032:Diet; D004100:Dihydroxycholecalciferols / Q000096:biosynthesis / Q000378:metabolism; D006887:Hydroxycholecalciferols / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism; D008297:Male; D010758:Phosphorus / Q000097:blood; D051381:Rats; D014808:Vitamin D Deficiency / Q000097:blood / Q000378:metabolism*
chemical_list: D002136:Calcium, Dietary; D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D010758:Phosphorus; D002118:Calcium