title: Mediation of calcium adaptation by 1,25-dihydroxycholecalciferol.
abstract: Vitamin D-depleted chicks which were repleted with 25-hydroxycholecalciferol adapted to the feeding of a low or high calcium diet by respectively increasing or decreasing their rate of intestinal calcium absorption. The synthesis of 1,25-dihydroxycholecalciferol in chicks fed differing calcium diets correlated directly with intestinal calcium absorption activity, suggesting that the intestinal calcium adaptation response is mediated by the modulation of kidney 25-hydroxycholecalciferol-1-hydroxylase activity. This view was strongly supported by the demonstration that repletion of the chicks with 1,25-dihydroxycholecalciferol eliminated the ability of the chicks to adjust their rates of intestinal calcium absorption to dietary levels of calcium.
mesh_terms: D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000378:metabolism; D000222:Adaptation, Physiological; D000818:Animals; D002136:Calcium, Dietary / Q000378:metabolism*; D004100:Dihydroxycholecalciferols / Q000494:pharmacology*; D006887:Hydroxycholecalciferols / Q000378:metabolism / Q000494:pharmacology*; D007408:Intestinal Absorption / Q000187:drug effects; D007668:Kidney / Q000201:enzymology; D008297:Male
chemical_list: D002136:Calcium, Dietary; D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase