Vitamin D status and brush border membrane vesicles: 1,25-dihydroxyvitamin D3 induced destabilization.
Purified chick duodenal brush border membrane vesicles (BBMV) were used to assess the effect of vitamin D on intestinal Ca2+ transport and membrane stability. BBMV preparations are right-side-out as judged by a nine-fold increase in accessibility of lactoperoxidase to core material actin in the presence of Triton X-100. Freshly prepared BBMV from vitamin D-deficient chicks support both sodium-dependent glucose transport and Ca2+ uptake. In vivo treatment with 1,25(OH)2D3 results in an 85% increase in the Vmax of Ca2+-uptake from 2.2 to 3.9 nmol/min/mg protein. The Km of Ca2+-uptake (0.9 mM) is independent of the vitamin D status of the chick. The majority of BBMV derived from vitamin D-replete chicks were destabilized and rendered incapable of supporting either sodium-dependent glucose uptake or Ca2+ uptake if they were held at 0-4 degrees C for 2 to 24 h. In 40 separate experiments, 80% of membranes derived from vitamin D-replete chicks showed characteristics of destabilization, whereas only 24% of all control membranes exhibited a lack of viability.
D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002645:Chickens; D003902:Detergents; D004386:Duodenum / Q000187:drug effects / Q000648:ultrastructure; D005947:Glucose / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism*; D017830:Octoxynol; D011092:Polyethylene Glycols; D014807:Vitamin D / Q000494:pharmacology*; D014808:Vitamin D Deficiency / Q000378:metabolism
D003902:Detergents; D014807:Vitamin D; D011092:Polyethylene Glycols; D017830:Octoxynol; D002117:Calcitriol; D005947:Glucose; D002118:Calcium