Summary
Isolated non blood-perfused intestinal segments from normal and irondeficient rats were used in vitro. A modification of the luminal perfusion method according to Fisher and Parsons allowed the comparison of iron and transferrin quantities in the serosal fluid at 15 min intervals. Iron transfer in jejunal and ileal segments was directly proportional to the luminal iron concentration within a dose range of 1 to 100 μmol/l, did not show saturation characteristics and was linear over time. Jejunal segments from iron-deficient rats transfered about twice as much iron as the jejunal controls. In ileal segments there was no difference in iron transfer between iron-deficient and control rats; in both cases transfer amounted to approx. 10% of jejunal controls. An exponential correlation was found, when the decreasing transferrin content of the tissue was plotted against the cumulative water transport. Transferrin and albumin release from jejunal and ileal segments into the absorbate cumulated asymptotically, which is typical for wash-out phenomena. As iron transfer cumulated linearly while transferrin release cumulated in an asymptotic manner, the capacity of transferrin to bind iron ions is exceeded roughly 100 times by molar equivalents of iron in the last absorbate fractions. Independence of iron transfer from mucosal transferrin quantities is concluded. As the molar transferrin/albumin ratios do not show significant differences between plasma and the sequence of absorbate samples, a wash-out from the gut's interstitial space is assumed, which makes plasma the most likely origin of transferrin in the mucosa.
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Becker G, Korpilla-Schäfer S, Osterloh K, Forth W (1979) Capacity of the mucosal transfer system and absorption of iron after oral administration in rats. Blut 38: 127–134
Delacroix DL, Hodgson HJF, McPherson A, Dive C (1982) Selective transport of polymeric immunoglobulin A in bile. J Clin Invest 70: 230–241
Dive C, Nadalini RA, Vaerman J-P, Heremans JF (1974) Origin and natur of the proteins of bile II. A comparative analysis of serum, hepatic lymph, and bile proteins in the dog. Eur J Clin Invest 4: 241–246
Fisher RB, Parsons DS (1949) A preparation of surviving rat small intestine for the study of absorption. J Physiol 110: 36–46
Forth W, Andres H (1969) Methode zur Erzeugung eines Eisenmangels bei Ratten. Drug Res 19: 363–364
Forth W, Rummel W (1973) Iron absorption. Physiol Rev 53: 724–792
Forth W, Rummel W, Seifen E (1965) Der Einfluß verschiedener Liganden auf Eisen-Durchtritt und -Bindung an isolierten Darmpräparaten normaler und anämischer Ratten. Naunyn-Schmiedebergs Arch Pharmacol 252: 224–241
Huebers H, Rummel W (1984) Protein-mediated epithelial iron transfer. In: Csaky TZ (Ed) Pharmacology of intestinal permeation Vol 70/I. Springer, Berlin, Heidelberg, New York, Tokyo, p 513–541
Isobe K, Isobe Y (1983) Localization of transferrin in rat duodenal mucosa by immunoperoxidase technique. Acta Haematol 46: 797–807
Osterloh K, Forth W (1981) Determination of transferrin-like immunoreactivity in the mucosal homogenate of the duodenum, jejunum, and ileum of normal and iron deficient rats. Blut 43: 227–235
Osterloh K, Schümann K, Ehtechami C, Forth W (1985) Transferrin in isolated cells from rat duodenum and jejunum. Blut 51: 41–47
Parmley RT, Barton JC, Conrade ME (1985) Ultrastructural localization of transferrin, transferrin receptor, and iron-binding sites on human placental and duodenal microvilli. Br J Haematol 60: 81–89
Richter E, Strugala GJ (1985) An all-glass perfusator for investigation of the intestinal transport and metabolism of foreign compounds in vitro. J Pharm Meth 14: 297–304
Saito K, Takaji N, Grasso JA, Aisen P (1986) Interaction of transferrin with iron-loaded rat peritoneal macrophages. Br J Haematol 62: 275–286
Schümann K, Schäfer SG, Forth W (1986) Iron absorption and billiary excretion of transferrin in rats. Res Exp Med (In press)
Schümann K (1984) Evidence for the independence of in vitro iron absorption from mucosal transferrin in rat jejunal segments. Gastroenterol Clin Biol 8 (II): 872 (Abstr)
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Supported by a grant of the Deutsche Forschungsgemeinschaft Fo 58/8-2. Part of the results has been presented during the VIth Meeting of the European Intestinal Transport Group [16]
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Schümann, K., Osterloh, K. & Forth, W. Independence of in vitro iron absorption from mucosal transferrin content in rat jejunal and ileal segments. Blut 53, 391–400 (1986). https://doi.org/10.1007/BF00321101
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DOI: https://doi.org/10.1007/BF00321101