Iron Transport by Rat Small Intestine in Vitro: Effect of Body Iron Status

S ummary . Both mucosal uptake and serosal transfer of iron by everted sacs of rat small intestine were maximal in the duodenum and decreased progressively towards the ileum. Transport of iron against a concentration gradient did not occur in any part of the intestine. When the iron concentration in the bathing medium was varied over the range 10–500 μM a saturable transport process was revealed in the proximal small intestine. In iron-deficient rats mucosal uptake of iron was increased but in iron-loaded rats it remained normal. The results suggest that iron transport across the proximal small intestine of the rat in vitro involves a carrier mechanism which responds adaptively to iron deficiency but not to overload.