Em. Wien et al., FERROUS IRON UPTAKE BY RAT DUODENAL BRUSH-BORDER MEMBRANE-VESICLES - EFFECTS OF DIETARY IRON LEVEL AND COMPETING MINERALS (ZN+2, MN+2, AND CA+2), Journal of nutritional biochemistry, 5(12), 1994, pp. 571-577
We sought to confirm a recent report that Fe+2 uptake into mt brush-bo
rder membrane vesicles is markedly increased by short-term consumption
of iron-deficient diet with no additional enhancement as the animal b
ecomes functionally iron-deficient with continuing dietary Fe deprivat
ion. In addition, we investigated whether previously observed in vivo
absorption interactions of iron, zinc, and manganese occur in the brus
h border membrane vesicles uptake process, and whether short-term or l
ong-term consumption of an iron-deficient diet affects the interaction
at the uptake level. We did not observe any differences in Fe+2 uptak
e between normal and iron-deficient brush border membrane vesicles, ev
en when the iron status contrast was intensified by feeding a high iro
n versus iron-deficient diet for 3 weeks. Equimolar Zn+2 and Mn+2 decr
eased Fe+2 uptake by 29 to 50% and II to 39%, respectively. Iron defic
iency did Plot alter these effects. Equimolar Fe+2 decreased Zn+2 upta
ke by 13 to 22%. Calcium, included as a negative control, did not affe
ct Fe+2 uptake. Thus, some competition between Fe+2 and similar divale
nt cations does occur at the level of the brush border membrane; the e
xact nature of this competition remains to be determined