Figure 3.

Glucose uptake in myotube-differentiated C2C12 cells. Fully myotube-differentiated C2C12 cells were cultured in a medium containing various concentrations of DDW for 48 h, after which the uptake of fluorescence-conjugated glucose was observed. TNF-α and resistin were added 24 h before harvesting, whereas insulin and fluorescence-conjugated glucose were added 30 min before harvesting. Scale bar: 100 μm. (a–c) Images of C2C12 glucose uptake. From the left, first and third rows indicate no insulin added; second and fourth rows indicate insulin added. The upper left two images are phase-contrast images of cells cultured in natural water medium (150 ppm) with and without insulin, respectively. The others are fluorescence observations. (a) Cells without induction of insulin resistance, (b) cells treated with 10 ng/mL TNF-α, and (c) cells treated with 10 μg/mL resistin. (d–f) Fluorescence intensity was measured, and the relative values to culture in natural water medium (150 ppm) without insulin were graphed. The sample size was four. * Significant difference (p < 0.05) between the presence (orange bar) and absence (blue bar) of insulin added to DDW medium at each concentration. (d) Cells without the induction of insulin resistance, (e) cells supplemented with 10 ng/mL TNF-α, and (f) cells supplemented with 10 μg/mL resistin.