Effect of Ca2+ and Mg2+ on the uptake of Fe3+ by mouse intestinal mucosa.
Initial Fe3+ uptake rates by mouse intestinal fragments were determined in vitro. Uptake was dependent primarily on the Fe3+-nitrilotriacetate complex concentration. Addition of Ca2+ and Mg2+ to the incubation medium had only small effects on the Fe3+ uptake rate. Duodenal fragments from hypoxic animals showed enhanced uptake of Fe3+; this increase was more pronounced with a divalent cation-free medium. Ca2+ markedly diminished the Fe3+ uptake by mucosa from hypoxic mice; Mg2+ had no appreciable effect. Distal ileal fragments exhibited lower uptake rates compared to the duodenum, but were more sensitive to the effects of added Ca2+. The ileal fragments did not show an adaptive response of Fe3+ uptake to hypoxia. These results suggest the existence of more than one pathway for mucosal Fe3+ uptake. One pathway, sensitive to Ca2+ and not stimulated by hypoxia, may be present in the duodenum and ileum. A second pathway, inhibited by Ca2+ and exhibiting an adaptive response to hypoxia, occurs only in the duodenum. This latter pathway is more sensitive to the effects of metabolic inhibitors.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002413:Cations, Divalent; D004386:Duodenum / Q000378:metabolism; D005290:Ferric Compounds / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism; D007082:Ileum / Q000378:metabolism; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D051379:Mice; D009571:Nitrilotriacetic Acid / Q000031:analogs & derivatives*
D002413:Cations, Divalent; D005290:Ferric Compounds; D008274:Magnesium; D009571:Nitrilotriacetic Acid; D002118:Calcium; C020326:ferric nitrilotriacetate