Mechanisms of absorption of caseinophosphopeptide bound iron
Résumé
Binding iron (Fe) to the 1-25 caseinophosphopeptide obtained from enzyme hydrolysis of β casein (β CPP) improves Fe bioavailability in the rat. To assess the mechanisms involved in its absorption, a perfused, vascularized duodenal rat loop model was used in controls and in Fe-deficient (bleeding of 25% blood volume) rats. Inhibitors of oxidative phosphorylation [2-4 dinitrophenol (DNP)] and/or of endocytosis [phenylarsine oxide (PAO)] were added to the perfusion solution containing 50 μM Fe as β CPP bound Fe (Fe-β CPP) or gluconate (Fe Gluc). Fe-β CPP enhanced Fe uptake, reduced mucosal storage, and improved net absorption both in controls and in deficient animals. DNP reduced uptake, mucosal storage, and net absorption by the same percentage in Fe-β CPP and Fe Gluc perfused rats in both control and Fe-deficient animals. PAO decreased uptake, mucosal storage, and net absorption of Fe-β CPP but not of Fe Gluc. At the end of the experiment Fe serum levels were increased only in Fe Gluc animals. These results confirm the improved bioavailability of β CPP bound Fe. They suggest that at least part of its absorption can occur by a different pathway than usual Fe salts. Fe-β CPP can be taken up by endocytosis and absorbed bound to amino acids or peptides.
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