The mechanism of iron exchange between synthetic iron chelators and rabbit reticulocytes

Abstract

The aim of this investigation was to examine the hypothesis that the mechanism of iron uptake by reticulocytes from synthetic iron chelators is dependent on an initial exchange of iron from the chelators to transferrin present in the cells. The experiments were performed with rabbit reticulocytes and transferrin, several iron chelators, and 59Fe to trace the movement of iron. The following results were obtained: 1. 1 The amount of transferrin present in rabbit reticulocytes after washing with ice-cold saline was found to be approx. 140 μg/ml cells. 2. 2 The relative rates of iron uptake by reticulocytes from chelators was shown to be directly related to rates at which iron exchanged between the chelators and transferrin. 3. 3 Depletion of cellular transferrin caused a marked reduction in the rate of iron uptake by reticulocyte from synthetic chelators but had much less effect on iron uptake from transferrin. 4. 4 Radioactive iron extracted from reticulocyte stroma after incubation of the cells with 59Fe labelled chelator solutions had the properties of transferrin-bound iron when studied by dialysis, immunoprecipitation, disc electrophoresis and gel filtration. The results of these experiments confirm the above hypothesis.