ENHANCED FE3-REDUCING CAPACITY DOES NOT SEEM TO PLAY A MAJOR ROLE IN INCREASING IRON-ABSORPTION IN IRON-DEFICIENT RATS()

Some eucaryotic organisms, including many plants, yeast and mice, have a higher iron uptake during iron deficiency because the capacity to r educe Fe3+ from the environment to Fe2+ is greatly enhanced. To determ ine whether this occurs in rats, a common experimental model for iron absorption in humans, we compared the in vivo capacity to reduce intra luminal Fe3+ in iron-deficient and normal rats. We also measured poten tial Fe3+-reducing components within the intestinal lumen and on the m ucosal surface. Iron-reducing capacity was higher in iron-deficient ra ts, by a significant (P = 0.026) but modest 20%, in parallel with high er mucosal weight (R(2) = 0.501, P = 0.003). In vitro iron reduction b y lumen contents was correlated with mucosal weight, even though mucos al tissue was not present in the assays. This capacity was not related to ascorbic acid, glutathione or other nonprotein sulfhydryls. Mucosa l ferric reductase activity was higher in iron-deficient rats in paral lel with higher tissue weight, but the specific activity did not diffe r and the higher total not associated with the brush border role of en dogenous Fe3+ reduction in regulating iron absorption should be invest igated in humans and in other experimental models.