Storage Iron Kinetics. VII. A BIOLOGIC MODEL FOR RETICULOENDOTHELIAL IRON TRANSPORT

Georges Fillet; James D. Cook; Clement A. Finch

doi:10.1172/JCI107703

Storage Iron Kinetics. VII. A BIOLOGIC MODEL FOR RETICULOENDOTHELIAL IRON TRANSPORT

Georges Fillet, James D. Cook, and Clement A. Finch

Published June 1, 1974 - More info

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Abstract

The processing of erythrocyte iron by the reticuloendothelial cell has been characterized by kinetic measurements of blood radioactivity made after the intravenous injection of heat-damaged erythrocytes labeled with ⁵⁹Fe and of transferrin-bound ⁵⁵Fe. The early reticuloendothelial release of iron, a matter of hours, was calculated from the plasma turnover rate of ⁵⁵Fe and the plasma reappearance of ⁵⁹Fe. Late release was calculated from the ratio of the cumulative incorporation of both tracers into the circulating red cell mass over a period of 2 wk. There was an initial processing period within the reticuloendothelial cell, after which radioiron either rapidly returned to circulation (t½ 34 min) or was transferred to a slowly exchanging pool of storage iron within the reticuloendothelial cell (t½ release to plasma of 7 days). These pathways were of equal magnitude in the normal dog. Reticuloendothelial release of iron was largely independent of the pre-existing plasma iron level or transferrin saturation. Diurnal fluctuations in the plasma iron level were shown to be the result of a variable partitioning of iron between the early and late release phases. Acute inflammation resulted in a prompt and marked increase in the fraction of iron stored (late phase), whereas depletion of iron stores resulted in a marked increase in early release.