Sustained elevation in extracellular glucose enhances NFAT5 nuclear translocation. Following the protocol described in Figure 1a, at 72 h after plating, fibers were transferred to isotonic or high d-glucose medium for 24 h; after this time, cells were fixed and assayed by immunofluorescence using a monoclonal NFAT5 antibody. (a and b) Representation of confocal images illustrating the distribution of NFAT5 (top panels) and DAPI staining (middle panels) in FDB fibers exposed to isotonic (a) or elevated (50 mmol/L) D-glucose (b). Merged images are shown in bottom panels. Asterisks in top panels (a) and (b) indicate a distinct pattern of fluorescent foci (1–3 foci per nucleus of about 1–3 μm in diameter). Scale bar: 5 μm. (c) Quantification of average nuclear translocation in control (n = 14 fibers, three mice) and d-glucose-exposed fibers (n = 14 fibers, three mice), measured as the ratio of nuclear/cytosolic NFAT5-Alexa-488 fluorescence measured in the regions of interest illustrated in (a) and (b). *Indicates P < 0.05 compared with control. NFAT5, nuclear factor of activated T-cell; DAPI, 4',6-diamidino-2-phenylindole; FDB, flexor digitorum brevis. (A color version of this figure is available in the online journal)