Mouse intestinal Fe3+ uptake kinetics in vivo. The significance of brush-border membrane vesicle transport in the mechanism of mucosal Fe3+ uptake.
Initial rates of mucosal uptake of Fe3+ from luminal Fe3+-nitrilotriacetate solutions by tied segments of mouse intestine in vivo have been measured. Duodenal uptake showed an approximately hyperbolic dependence of uptake on Fe3+ complex concentration (Km(app) 66 microM, Vmax 6.2 pmol/min per mg intestine) with little dependence on nitrilotriacetate:Fe3+ ratio or on added Ca2+. Duodenal uptake was greatly stimulated by hypoxic treatment of mice. Uptake rates by distal ileum were lower than by duodenum and more sensitive to added Ca2+. These results show that isolated duodenal brush-border membrane Fe3+ transport characteristics (Simpson, R.J. and Peters, T.J. (1984) Biochim. Biophys. Acta 772, 220-226) are inadequate to explain duodenal Fe3+ uptake in vivo. However, ileal uptake can be explained by the properties of isolated ileal brush-border membrane (Simpson, R.J., Raja, K.B. and Peters, T.J. (1985) Biochim. Biophys. Acta 814, 8-12).
D000818:Animals; D001692:Biological Transport; D004386:Duodenum / Q000378:metabolism; D005290:Ferric Compounds / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007082:Ileum / Q000378:metabolism; D066298:In Vitro Techniques; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D051379:Mice; D008871:Microvilli / Q000378:metabolism
D005290:Ferric Compounds; D007501:Iron