Fe2+ uptake by mouse intestinal mucosa in vivo and by isolated intestinal brush-border membrane vesicles.
In vivo kinetics of mucosal uptake of luminal 59Fe2+ by tied segments of normal mouse duodenum are characterised by a Km of approx. 100 microM and a Vmax of approx. 9 pmol/min per mg wet weight of intestine. These values were determined at pH 7.25 in the presence of excess sodium ascorbate. Studies with luminal Fe2+ concentrations of 100 microM reveal: uptake is relatively independent of ascorbate: Fe ratio and luminal pH and uptake is potently inhibited by 1 mM Co2+ or Mn2+ and large luminal NaCl concentrations but not by Ca2+. 3 days of hypoxia (0.5 atmospheres) yields no significant increase in subsequent total mucosal uptake by in vivo tied segments while uptake is significantly reduced by semi-starvation. Quantitative comparison of in vivo mucosal uptake with subsequent determination of isolated brush-border membrane 59Fe2+ transport in individual mice reveals a positive correlation (P less than 0.01) between the two parameters. These results, in conjunction with studies of isolated mouse duodenal brush-border membrane (Simpson, R.J. and Peters, T.J. (1985) Biochim. Biophys. Acta, 814, 381-388 and (1986) Biochim. Biophys. Acta 856, 109-114) suggest that the Fe2+ transport properties of isolated brush-border membrane are quantitatively adequate to explain in vivo mucosal uptake in normal and hypoxic mice at Fe2+ concentrations up to 100 microM.
D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D001692:Biological Transport; D003035:Cobalt / Q000494:pharmacology; D004386:Duodenum / Q000378:metabolism; D005296:Ferrous Compounds / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000378:metabolism; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D007504:Iron Radioisotopes; D007700:Kinetics; D008297:Male; D008345:Manganese / Q000494:pharmacology; D051379:Mice; D008871:Microvilli / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology
D005296:Ferrous Compounds; D007504:Iron Radioisotopes; D003035:Cobalt; D008345:Manganese; D012965:Sodium Chloride; D007501:Iron; D001205:Ascorbic Acid