Fig. 6.

Insulin stimulation fails to increase glucose uptake in human airway epithelia expressing F508del-CFTR. A: primary hBE cells were treated with bilateral insulin (black bars) for a total of 15 min in the presence of 2-deoxy-d-[³H]glucose to measure glucose uptake and retention within the cell layer. Cells were also treated with cytochalasin B (gray bars) to inhibit fusion of Glut4 storage vesicles (GSVs) to the plasma membrane. Unstimulated control cells are represented by white bars. NhBE cells responded to insulin by increasing their glucose uptake, whereas CFhBE cells did not respond to insulin. Cytochalasin B (CytoB) treatment prevented the full effect of insulin stimulation in NhBE cells but had no effect in CFhBE cells. B: comparably treated NuLi-1 and CuFi-5 cells had insulin stimulation responses similar to those seen in NhBE and CFhBE, respectively; n = 4 filters for each data point for each graph. C: temporal glucose uptake measurements indicated that CuFi-5 cells did not respond to treatment with bilateral insulin (■) and behaved similarly to unstimulated CuFi-5 cells (□) and unstimulated NuLi-1 cells (○) compared with stimulated NuLi-1 cells (●). D: NuLi-1 or CuFi-5 filters were pretreated with apical insulin solution for 15 min before measuring the uptake of 2-deoxy-d-[³H]glucose. The basolateral solution contained neither glucose nor insulin. Apical stimulation resulted in apical glucose uptake in NuLi-1 cells but not in CuFi-5 cells; n = 18 filters for each data bar. All data are shown as means ± SE where *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001, and ****P ≤ 0.0001 by unprotected two-way ANOVA Fisher’s LSD test.