[Effects of hypoxia on iron metabolism of rat L6 skeletal muscle cells].

ABSTRACT

The present study was aimed to investigate the effects of hypoxia on iron metabolism of skeletal muscle. Rat L6 skeletal muscle cells were randomly divided into three groups which were exposed to hypoxia (1% O(2)) for 0, 12, 24 h, respectively. Iron isotope tracing method was used to determine iron uptake and release. Iron content of labile iron pool (LIP) was investigated by flow cytometry, and the expressions of transferrin receptor 1 (TfR1), divalent metal transporter 1 (DMT1), ferroportin 1 (FPN1), hypoxia-inducible transcription factor-1 (HIF-1) in L6 cells were observed by Western blot. The results showed that, compared with 0-hour hypoxia group, 12-hour hypoxia group exhibited significantly increased iron uptake and LIP (P < 0.05), as well as decreased iron release (P < 0.01). Not only iron uptake and release, but also LIP in 24-hour hypoxia group were significantly decreased, compared with those in 0- and 12-hour hypoxia groups (P < 0.01). The expressions of HIF-1, DMT1 (IRE), DMT1 (non-IRE) and TfR1 in 12-hour hypoxia group were significantly increased compared with those in 0-hour hypoxia group (P < 0.01). On the contrary, the expressions of DMT1 (IRE), DMT1 (non-IRE) and FPN1 in 24-hour hypoxia group were significantly decreased compared with those in the other two groups. However, TfR1 expression in 24-hour hypoxia was higher than those in 0- and 12-hour hypoxia groups (P < 0.05 or P < 0.01). These results suggest hypoxia plays an important role in iron metabolism of skeletal muscle cells. Moderate hypoxia can increase iron uptake and decrease iron release, resulting in higher LIP, but a prolonged hypoxia induces a disordered iron metabolism of skeletal cells.