Vitamin D Activates (Na+-K+)ATPase: A Possible Regulation of Phosphate and Calcium Uptake by Cultured Embryonic Chick Small Intestine
The effect of vitamin D3 and of its biologically most active metabolite, 1,25-dihydroxyvifamin D3, on intestinal calcium and inorganic phosphate (Pi) absorptive mechanisms has been studied extensively in an organ culture system of embryonic chick small intestine (Corradino, 1973; Peterlik, 1978; Cross and Peterlik, 1982). Elevation of Ca and Pi uptake by vitamin D depends on prior gene activation by the sterol (cf. also Franceschi and DeLuca, 1981b). However, this vitamin D action is only partially expressed in undifferentiated absorptive cells, since they respond to the sterol solely by an increase in Ca but not in Pi uptake. Induction of the latter has been shown to require advanced target cell maturation (Cross and Peterlik, 1982).
KeywordsEmbryonic Chick Sodium Pump Jejunal Segment Intestinal Brush Border Membrane Vesicle Contralateral Plasma Membrane
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