Uptake of Radioiron in Tissue Storage Compounds in Normal and Hemosiderotic Mice and Its Utilization for Erythropoiesis

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Abstract
Livers of mice were separated into ferritin-rich fractions (FRF) and hemosiderin-rich fractions (HRF). The effects of hemosiderosis and hemorrhage on distr. of an intraven. 75 /ug. dose of radioiron (Fe*) among these liver fractions, spleen, kidney and blood, was studied. In normal mice the amt. of injected Fe* taken up by the FRF was directly related to the amt. of non-radioactive Fe already present. In mice made hemosiderotic with sac-charated Fe oxide a greater uptake of Fe* by the FRF was observed. The HRF contained the same amt. of Fe* in normal and hemosiderotic mice. Both the HRF and FRF contained 6-8 times the normal amt. of total Fe. Fe* uptake by kidney and spleen was unaffected by hemosiderosis. Blood radioactivity of hemosiderotic mice was 1/2 that of normals 4 days after Fe* injn., the time of death and tissue sampling. This indicates either suppression of red blood cell formation or failure of Fe* to mix completely with the non-radioactive Fe stores. Hemorrhage (avg. 206 Mg. of blood Fe) caused a reduction in Fe* in the FRF of 98% and in total Fe of 50%. The total Fe of the HRF was little affected, but 93% of the Fe*was removed following the hemorrhage. This supports the thesis that the last Fe received is the 1st used for erythropoiesis and that Fe does not mix homogeneously in the storage compounds.