Studies on Fe complexes produced by yeast. IV. Mechanism of Fe transport from an Fe(II)-oligosaccharide complex across the mucosal membrane of the rat intestine.
The mechanism of Fe transport across the rat duodenal membrane from an Fe(II)-oligosaccharide complex (designated B1-c) produced in wine by yeast and showing high hematopoietic activity in rats was examined. The Fe uptake from B1-c by brush border membrane (BBM) vesicles isolated from the rat intestine was based mainly on the Fe binding to membrane components which were suggested to be inside the vesicles. Evidence that Fe was transported into the vesicles by a special transport system other than simple diffusion was obtained by observing saturation kinetics under conditions of isotope exchange, and temperature and pH dependence. This Fe uptake was not inhibited by any metal ions tested, including inorganic Fe(II), and the BBM vesicles from the duodenum had a higher Fe uptake than those from the other parts of the small intestine. Furthermore, the BBM vesicles isolated from rats with Fe deficiency showed a significantly increased Fe uptake. The Km value for B1-c uptake was 0.16 mM, lower than the values for FeSO4 and ferrous ascorbate. These results suggest that a special transport system selective for B1-c may be present on the mucosal membrane. B1-c was taken up by the BBM vesicles in the form of Fe-oligosaccharide complex. From the preloaded vesicles, B1-c was released temperature- and pH-dependently.(ABSTRACT TRUNCATED AT 250 WORDS)
Tabata
S
S
Tanaka
K
K
D000818:Animals; D066298:In Vitro Techniques; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism*; D007501:Iron / Q000493:pharmacokinetics*; D007504:Iron Radioisotopes; D008297:Male; D009844:Oligosaccharides / Q000493:pharmacokinetics*; D051381:Rats; D011919:Rats, Inbred Strains
D007504:Iron Radioisotopes; D009844:Oligosaccharides; D007501:Iron