title: Calcium transport by rat duodenal villus and crypt basolateral membranes.
abstract: Rat duodenal cells were isolated sequentially to give fractions enriched for villus and crypt cells. From each of these fractions, basolateral-enriched membrane vesicles were prepared and ATP-dependent calcium uptake was studied. Calcium uptake was sensitive to temperature, was inhibited by vanadate and by A23187, and was lower in vitamin D-deficient animals. In normal animals, calcium transport was approximately twofold greater in villus-tip than in crypt cell-fraction basolateral membranes though the affinity of the uptake for calcium was similar (Km = 0.3 microM). In vitamin D-deficient animals, the crypt-to-villus gradient was reduced, and in all fractions, calcium transport was similar to or lower than that in the crypts of normal animals. Six hours after vitamin D-deficient animals were repleted with 1,25-dihydroxycholecalciferol, a significant increase in calcium transport by everted gut sacs was present; however, basolateral calcium transport was significantly increased in only the mid-villus fractions, and no change was seen in the villus-tip fractions. Thus vitamin D appears necessary for the development of increased basolateral membrane calcium pump activity in duodenal villus cells, but not all cells in vitamin D-deficient rats are able to respond to 1,25-dihydroxycholecalciferol.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D000001:Calcimycin / Q000494:pharmacology; D002117:Calcitriol / Q000627:therapeutic use; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002469:Cell Separation; D004386:Duodenum / Q000166:cytology / Q000378:metabolism*; D007473:Ion Channels / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051381:Rats; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology; D014808:Vitamin D Deficiency / Q000188:drug therapy / Q000378:metabolism
chemical_list: D007473:Ion Channels; D014639:Vanadium; D000001:Calcimycin; D014638:Vanadates; D000255:Adenosine Triphosphate; D002117:Calcitriol; D002118:Calcium