Iron absorption in the rat: the search for possible intestinal mucosal carriers.

The biological relevance of four iron-containing fractions previously detected in rat intestinal mucosal cells has been studied. The distribution of iron in these fractions obtained by chromatography on Sepharose 6B has been examined after in vivo and in vitro incubation of mucosal cells with 59Ce. In addition, the effects of phenobarbitone, cycloheximide, iron-deficiency and iron-loading on the uptake and distrubution of iron within the four mucosal cell fractions was studied. The iron in fraction I was mostly bound to intracellular membrane particles. Fraction II was shown to be ferritin. Fraction III contained some transferrin and also a protein of molecular weight similar to transferrin but which was not precipitable by antitransferrin antiserum. Quantited with the results of 'chaser' experiments suggested that, in addition to ferritin, at least two of the fractions (I and III) were involved in the process of iron absorption by the mucosal cell.