Ontogeny of iron uptake across brush border membrane of guinea pig duodenum and its autoradiographic localisation.

Although the neonatal guinea pig has substantial body iron stores, the rate of duodenal iron absorption is greater than in the mature animal. Here we have used brush border membrane vesicles and biopsy tissue to examine the role of the brush border in changes in Fe2+ and Fe3+ uptake by the duodenum of newborn and adult guinea pigs. We conclude that the brush border membrane is unlikely to be an important site for developmental alterations in iron absorption. Autoradiographic analysis of Fe2+ uptake, however, implies that whilst only the upper villus cells of adult duodenal villi are involved in iron uptake, all enterocytes in the neonate display this function.