title: 25-Azavitamin D3, an inhibitor of vitamin D metabolism and action.
abstract: 25-Azavitamin D3 inhibited both the bone calcium mobilization and intestinal calcium transport responses of rats to vitamin D3 but not to 25-hydroxyvitamin D3. Although 25-azavitamin D3 had no effect on the response of bone to 1alpha,25-dihydroxyvitamin D3, it did diminish the response of the intestine to that metabolite. 25-Azavitamin D3 increased liver vitamin D content and reduced the concentration of 25-hydroxyvitamin D3 required to inhibit the metabolism of vitamin D3 (75 and 200 microgram) were similar to the doses of 25-azavitamin D3 required to inhibit the action of vitamin D3 in vivo (50 and 150 microgram). 25-Azavitamin D3 is thus a vitamin D antagonist, acting for the most part via inhibition of the liver 25-hydroxylation of vitamin D3.
mesh_terms: D000818:Animals; D001681:Biological Assay; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002762:Cholecalciferol / Q000494:pharmacology* / Q000031:analogs & derivatives; D004100:Dihydroxycholecalciferols / Q000494:pharmacology*; D004386:Duodenum / Q000187:drug effects / Q000378:metabolism; D006887:Hydroxycholecalciferols / Q000494:pharmacology*; D007408:Intestinal Absorption / Q000187:drug effects; D008099:Liver / Q000378:metabolism; D008297:Male; D051381:Rats; D014807:Vitamin D / Q000378:metabolism*
chemical_list: D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D014807:Vitamin D; D002762:Cholecalciferol; C019265:25-azavitamin D3; D002118:Calcium