Abstract: Abstract Objective: To explore the effect of conditioned media (CM) from nomoxia- and hypoxia-treated macrophages on insulin-regulated glucose transporter 4 (GLUT4) in skeletal muscle cells. Methods: The macrophages were cultured under normoxia or hypoxia condition, respectively. Then conditioned media were collected and used to incubate C2C12GLUT4myc skeletal muscle cells. The levels of GLUT4myc on the cell surface were measured by an antibody-coupled absorbance assay. The mRNA expression of TNF-α in macrophages was determined by real-time PCR. The levels of TNF-α in the media of macrophages were determined by ELISA. Results: The increase of insulin-stimulated GLUT4myc translocation was significantly impaired under incubation with CM from both nomoxia- and hypoxia-treated macrophages (P<0.01). Both mRNA and protein expression of TNF-α were significantly higher in CM from hypoxia-treated macrophages than nomoxia-treated ones (P<0.05). But there was no difference between two CMs on insulin function in skeletal muscle cells. Conclusion: Both CM from nomoxia- and hypoxia-treated macrophages directly induce insulin resistance in skeletal muscle cells. CM from hypoxia-treated macrophages does not worsen insulin resistance.

Key words: Macrophages, Hypoxia, Conditioned medium, C2C12GLUT4myc, Translocation.