title: Serum calcium and vitamin D regulate 1,25-dihydroxyvitamin D3 receptor concentration in rat kidney in vivo.
abstract: The effects of vitamin D status, serum calcium, and serum phosphorus levels on 1,25-dihydroxyvitamin D receptor levels in kidney were investigated. Weanling rats were fed for 4 weeks on a diet with various levels of calcium and phosphorus with or without vitamin D. The 1,25-dihydroxyvitamin D3 receptor concentration in kidney was determined by an immunoradiometric assay. In the absence of vitamin D, total receptor concentration is increased 2-fold by an increase in serum calcium concentration. At normal serum calcium levels, the administration of vitamin D resulted in a 5-fold increase in receptor concentration. In hypocalcemic animals, however, vitamin D did not change receptor levels. Serum phosphorus levels could not be linked to any changes in 1,25-dihydroxyvitamin D3 receptor concentration. This study demonstrates that serum calcium levels and vitamin D regulate 1,25-dihydroxyvitamin D3 receptor concentration in vivo in kidney. On the other hand, vitamin D is unable to exert control of receptor levels in kidney under hypocalcemic conditions.
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, College of Agricultural and Life Sciences 53706.
authors.forename: M E
authors.initials: ME
authors.lastname: Sandgren
authors.forename: H F
authors.initials: HF
authors.lastname: DeLuca
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D003600:Cytosol / Q000378:metabolism; D007118:Immunoassay; D007668:Kidney / Q000378:metabolism*; D008297:Male; D010758:Phosphorus / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000378:metabolism*; D014807:Vitamin D / Q000502:physiology*
chemical_list: D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D014807:Vitamin D; D010758:Phosphorus; D002117:Calcitriol; D002118:Calcium