Phosphate transport by plasma membranes of enterocytes during development: role of 1,25-dihydroxycholecalciferol.
The present studies were designed to investigate phosphate transport across the brush border and basolateral membranes of enterocytes and to determine the effect of 1,25-dihydroxycholecalciferol [1,25(OH)2D3] on these processes in suckling and adolescent rats. Vitamin D deficiency was induced in suckling rats by feeding pregnant dams a vitamin D-deficient diet 48 h after insemination; they were then kept in the dark. Vitamin D deficiency in the adolescent rats was induced by feeding the vitamin D-deficient diet to weanling rats for 4 wk. V max values for Na(+)-dependent phosphate uptake in the brush border membranes of vitamin D-deficient and 1,25(OH)2D3-injected suckling rats was 0.7 +/- 0.1 and 1.5 +/- 0.2 nmol.mg protein-1.10 s-1 (P less than 0.01), respectively; V max values in adolescent rats were 0.2 +/- 0.05 and 0.36 +/- 0.04 nmol.mg protein-1.10 s-1 (P less than 0.05), respectively. Vmax values for Na(+)-dependent phosphate uptake in basolateral membranes of vitamin D-deficient and 1,25(OH)2D3-treated suckling rats were 0.006 +/- 0.001 and 0.047 +/- 0.006 nmol.mg protein-1.10 s-1 (P less than 0.01).
Ghishan
F K
FK
Department of Pediatric Gastroenterology/Nutrition, Vanderbilt University Medical Center, Nashville, TN.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002117:Calcitriol / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism; D007408:Intestinal Absorption / Q000187:drug effects*; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects / Q000254:growth & development*; D007700:Kinetics; D007931:Leucyl Aminopeptidase / Q000378:metabolism; D008871:Microvilli / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000378:metabolism
D010710:Phosphates; D012964:Sodium; D007931:Leucyl Aminopeptidase; D000254:Sodium-Potassium-Exchanging ATPase; D002117:Calcitriol