Characterization of Phosphate Uptake in Isolated Chick Intestinal Cells

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Abstract
The action of vitamin D on phosphate homeostasis and, specifically, intestinal phosphate transport has assumed an increasingly prominent role in the overall physiologic action of vitamin D. More rapid advances in this area are limited by the available experimental models for the study of intestinal phosphate transport. In vitro tissue preparations are required to eliminate the systemic metabolism of vitamin D to both active and inactive derivatives. In the past, such in vitro preparations have involved intact tissue (1–3). The interpretation of those studies utilizing these preparations is complicated by the large extracellular space and paracellular transport. Secondly, the physiologic site of vitamin D action, the basal-lateral membrane, is not accessible to the vitamin in these in vitro incubations. For these reasons a preparation of isolated intestinal cells was evaluated as an experimental model for the study of phosphate transport and the influence of vitamin D on the cellular accumulation of phosphate.