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Rat duodenal IRP1 activity and iron absorption in iron deficiency and after H 2 O 2 perfusion
Author(s) -
Schümann K.,
Brennan K.,
Weiss M.,
Pantopoulos K.,
Hentze M. W.
Publication year - 2004
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.2004.01335.x
Subject(s) - duodenum , iron deficiency , crypt , absorption (acoustics) , perfusion , chemistry , jejunum , medicine , in vivo , endocrinology , metabolism , biochemistry , biology , materials science , anemia , microbiology and biotechnology , composite material
Background Iron regulatory protein 1 (IRP1), a post‐transcriptional regulator of iron metabolism, is activated in the duodenum of iron‐deficient animals, which is associated with increased iron absorption. In cell cultures IRP1 was also activated by iron‐independent signals, such as H 2 O 2 . Here we investigate whether luminal perfusion of rat duodenum with H 2 O 2 activates duodenal IRP1 and modulates duodenal iron absorption. Methods Duodena from iron‐adequate Sprague‐Dawley rats were luminally perfused with H 2 O 2 . Iron regulatory protein‐1 activity was determined in duodenal mucosa or in villus and crypt preparations by an electrophoretic mobility shift assay. Duodenal 59 Fe absorption was measured in isolated, perfused duodenal segments ex vivo and in ligated loops in vivo . 59 Fe uptake from the blood side was assessed after i.v. injection of 59 Fe‐nitrilotriacetic acid. Results Similar to iron deficiency, the perfusion with 0–50 mM of H 2 O 2 increases duodenal IRP1 activity along the entire crypt villus‐axis in a dose‐dependent manner. After H 2 O 2 treatment, IRP1 remains activated for 12–24 h in the tips and for 72 h in the crypts. In iron‐deficiency, IRP activation correlates with increased 59 Fe absorption. However, the H 2 O 2 treatment fails to stimulate any increase in 59 Fe uptake, without promoting damage of mucosal architecture or impairing glucose and water transport. Conclusion Duodenal 59 Fe uptake is not affected by the H 2 O 2 ‐mediated activation of IRP1.