Biochemical characterization of 1,25(OH)2D3 receptors in chick embryonal duodenal cytosol.
This study presents measurements of serum vitamin D metabolites, calcium and phosphorus as well as measurements of the equilibrium dissociation constant for duodenal 1,25(OH)2D3 receptor in 15-, 18-, 19-, and 20-day chick embryos in comparison to that in 1- and 118-day-old chicks and to vitamin D-deficient chicks. The present results showed that: (a) serum 1,25(OH)2D and 24,25(OH)2D levels rise from 15 and 18 to days 19 and 20 of embryonic development while serum phosphate levels are stable; (b) serum calcium levels rise at hatching to adult levels; (c) the duodenal 1,25(OH)2D3 receptor is detectable in 15-day-old embryo and has a Kd similar to that of 118-day-old vitamin D-replete chicks; and (d) the activity of 1,25(OH)2D3 receptor in chick duodenal cytosol is maximal at hatching.
D000818:Animals; D001667:Binding, Competitive; D002117:Calcitriol / Q000378:metabolism*; D002118:Calcium / Q000097:blood; D002642:Chick Embryo; D003600:Cytosol / Q000378:metabolism; D004100:Dihydroxycholecalciferols / Q000097:blood; D004386:Duodenum / Q000196:embryology* / Q000378:metabolism; D007700:Kinetics; D010710:Phosphates / Q000097:blood; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000378:metabolism*; D014808:Vitamin D Deficiency / Q000378:metabolism
D004100:Dihydroxycholecalciferols; D010710:Phosphates; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D002117:Calcitriol; D002118:Calcium