Iron transport by isolated rat intestinal mucosal cells.

In vitro uptake of radioiron by suspensions of isolated rat duodenal mucosal cells has been examined. The cells bind iron avidly, with uptakes of 15 to 20% after 20 min of incubation. Uptake is dependent upon temperature, pH, and iron and cell concentration. It is unaffected by inhibitors of cellular respiration but is blocked in a concentration-dependent fashion by iron-chelating agents. Iron-deficient cells take up iron at the same rate as normal cells. Binding by brush borders appears to account for 50 to 60% of the total uptake by isolated cells. In vitro radioiron uptake by isolated cells occurs by passive diffusion, is not regulated by the animal's iron status, and is primarily a function of bioavailability of iron in the incubating medium. If the model reflects the behavior of cells in vivo, the initial uptake of iron by the mucosa is a passive process which may serve to concentrate dilute luminal iron at the mucosal surface in preparation for absorption.