title: The effect of Prednisolone upon the metabolism and action of 25-hydroxy-and 1,25-dihydroxyvitamin D3.
abstract: Treatment of vitamin D-deficient rats with Prednisolone(R) does not alter the rate of conversion of [(3)H]25-hydroxyvitamin D(3) to [(3)H]1,25-dihydroxyvitamin D(3), but the further conversion of [(3)H]1,25-dihydroxyvitamin D(3) to a more polar metabolite is more rapid in the Prednisolone(R)-treated animals. This more polar metabolite is biologically inactive, periodate-insensitive, and persists in the intestine as long as 1,25-dihydroxyvitamin D(3). Also, the time course of action of 1,25-dihydroxyvitamin D(3) upon intestinal calcium transport is altered by Prednisolone(R) treatment. Treatment with Prednisolone(R) did not change the magnitude of the initial response to 1,25-dihydroxyvitamin D(3) at 7 hr, but did decrease the response at 24 and 48 hr after a single dose of 1,25-dihydroxyvitamin D(3). The present results show that one of the means by which large doses of adrenal corticoids alter intestinal calcium transport is by stimulating the further metabolism of 1,25-dihydroxyvitamin D(3) to a more polar, biologically inactive intestinal metabolite.
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D004100:Dihydroxycholecalciferols / Q000378:metabolism* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006887:Hydroxycholecalciferols / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010024:Osteoporosis / Q000517:prevention & control; D011239:Prednisolone / Q000494:pharmacology* / Q000627:therapeutic use; D051381:Rats; D014316:Tritium; D014808:Vitamin D Deficiency / Q000378:metabolism
chemical_list: D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D014316:Tritium; D011239:Prednisolone; D002118:Calcium