Response of renal calcium-binding protein. Independence of kidney vitamin D hydroxylation.
Dietary calcium and dietary phosphorus restriction were studied in chicks fed either cholecalciferol or 1alpha-hydroxycholecalciferol. Intestinal calcium absorption and calcium-binding protein of 1alpha-hydroxycholecalciferol-treated chicks remained unchanged under dietary calcium restriction, but increased under dietary phosphorus restriction. Kidney calcium-binding protein was not altered by dietary caclium restriction in chidks treated with either cholecalciferol or 1alpha-hydroxycholecalciferol, but increased under dietary phosphorus restriction independent of the vitamin D source. In contrast to the intestine, calcium-binding activity of the kidney was found to be poorly related to the calcium-binding protein concentration. It is suggested that kidney calcium-binding protein is regulated by a mechanism different from that of intestinal calcium-binding protein, and that its concentration in renal tissue is related to renal caclium excretion or plasma calcium level.
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002136:Calcium, Dietary; D002645:Chickens; D002762:Cholecalciferol / Q000378:metabolism; D006887:Hydroxycholecalciferols / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010710:Phosphates / Q000494:pharmacology; D011955:Receptors, Drug / Q000187:drug effects; D014807:Vitamin D / Q000378:metabolism*
D002136:Calcium, Dietary; D006887:Hydroxycholecalciferols; D010710:Phosphates; D011955:Receptors, Drug; D014807:Vitamin D; D002762:Cholecalciferol; D002118:Calcium