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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.
R J Simpson, and
K B Raja, and
T J Peters
April 1985,
Biochimica et biophysica acta,
R J Simpson, and
K B Raja, and
T J Peters
April 1991,
Gut,
R J Simpson, and
K B Raja, and
T J Peters
July 1992,
Biochemistry international,
R J Simpson, and
K B Raja, and
T J Peters
September 1991,
Biochimica et biophysica acta,
R J Simpson, and
K B Raja, and
T J Peters
January 1990,
The Journal of antimicrobial chemotherapy,
R J Simpson, and
K B Raja, and
T J Peters
November 1985,
The Journal of clinical investigation,
R J Simpson, and
K B Raja, and
T J Peters
December 1984,
Biochimica et biophysica acta,
R J Simpson, and
K B Raja, and
T J Peters
July 1999,
Biological & pharmaceutical bulletin,
R J Simpson, and
K B Raja, and
T J Peters
May 1996,
The Journal of pharmacy and pharmacology,
R J Simpson, and
K B Raja, and
T J Peters
December 1998,
Biological & pharmaceutical bulletin,
