Twenty-five healthy mountaineers were studied. Blood samples and duodenal biopsies were taken at baseline of 446 m as well as on day 2 (MG2) and 4 (MG4) after rapid ascent to 4559 m. Divalent metal-ion transporter 1 (DMT-1), ferroportin 1 (FP-1) messenger RNA (mRNA), and protein expression were analyzed in biopsy specimens by quantitative reverse-transcription polymerase chain reaction (RT-PCR) and immunohistochemistry. Serum hepcidin levels were analyzed by mass spectrometry. Serum iron,

buy CHIR-99021 ferritin, transferrin, interleukin (IL)−6, and C-reactive protein (CRP) were quantified by standard techniques. Serum erythropoietin and growth differentiation factor 15 (GDF15) levels were measured by enzyme-linked immunosorbent assay (ELISA). Under hypoxia, erythropoietin peaked at MG2 (P < 0.001) paralleled by increased GDF15 on MG2 (P < 0.001). Serum iron and ferritin levels declined rapidly on MG2 and MG4 (P < 0.001). Duodenal DMT-1 and FP-1 mRNA expression increased up to 10-fold from baseline on MG2 and

MG4 (P < 0.001). selleck products Plasma CRP increased on MG2 and MG4, while IL-6 only increased on MG2 (P < 0.001). Serum hepcidin levels decreased at high altitude on MG2 and MG4 (P < 0.001). Conclusion: This study in healthy volunteers showed that under hypoxemic conditions hepcidin is repressed and duodenal iron transport is rapidly up-regulated. These changes may increase dietary iron uptake and allow release of stored iron to ensure a sufficient

iron supply for hypoxia-induced compensatory erythropoiesis. (Hepatology 2013; 58:2153–2162) Iron is an essential trace element required as a component of various molecules that sense, transport, and store oxygen.[1] Availability of sufficient MCE amounts of iron is critically important for normal and stress-induced erythropoiesis. Circulating iron levels are affected by intestinal absorption from the diet, iron transport capacity of the blood, iron losses via bleeding and cellular desquamation, and the release of iron from cells such as macrophages and hepatocytes.[2] Inorganic iron is absorbed at the brush border of duodenal enterocytes by the divalent metal-ion transporter 1 (DMT-1; SLC11A2) following reduction by a membrane-associated ferrireductase. Cytosolic iron can be exported by the basolateral iron transporter ferroportin (FP-1; SLC40A1)[3, 4] and subsequently undergoes oxidation by the multicopperoxidase hephaestin before being incorporated into circulating transferrin. Systemic iron content is tightly regulated,[1, 4, 5] because accumulation of intracellular iron causes cell and tissue damage, presumably by iron-catalyzed generation of reactive oxygen species.[5, 6] Hepcidin, a liver-derived 25 amino acid peptide hormone, has been identified as the key regulator of iron homeostasis[7, 8] (reviewed[6, 9]).