Fig. 3. Piezo1 is important for swelling-induced insulin secretion.
a [Ca2+]i in INS-1 832/13 cells (measured using Fura-2 fluorescence; Fi) normalized to the basal (F0) in cells superfused with 2.8 mM glucose before and during exposure to hypotonic solutions (‘hypo’) in the absence (black) or presence (red) of GsMTx4 followed by stimulation with 70 mM K+ as indicated. b Average of increase in AUC above basal for hypotonic stimulation with or without GsMTx4 treatment in a (n = 85 and 81 cells for Ctrl and GsMTx4 treatment, respectively, p < 0.0001). c As in a but in control cells (si-Ctrl) and after silencing of Piezo1 (si-Piezo1) superfused as indicated. d As in b but in control cells (si-Ctrl) and after silencing of Piezo1 (si-Piezo1) for c (n = 164 and 156 cells for control and si-Piezo1, respectively, p < 0.0001). e As in a but changes in membrane potential ∆ψp measured using PMPI. f Average of increase in AUC above basal for changes in ∆ψp induced by the superfusion medium with or without GsMTx4 for e (n = 71 and 62 cells for control and GsMTx4, respectively, p < 0.0001). g Insulin secretion in INS-1 832/13 cells in isotonic (~320 mOsm) or hypotonic buffer (~200 mOsm) with or without GsMTx4 (n = 4) as indicated, p values for the comparison between isotonic and hypotonic stimulation without/with GsMTx4 treatment are 0.0003, 0.7647, respectively, p value for the comparison between hypotonic stimulation without/with GsMTx4 is 0.0002. h Insulin secretion in INS-1 832/13 cells under shear stress (ss) with or without GsMTx4 in isotonic 2.8 mM glucose secretion buffer (n = 8), p values for the comparison between Ctrl and ss without/with GsMTx4 treatment are 0.0095, 0.0075, respectively. Data are presented as box Tukey plot in figures b, d, and f. In g and h, dot plots of individual experiments with mean values ± SEM are shown. The definition of box Tukey is as indicated as in Fig. 1. Evaluation of statistical significance was done using unpaired two-tailed Student’s t-test in figure b, d, and f, two-way ANOVA multiple comparisons in g. In h, statistical significances were evaluated by one-way ANOVA multiple comparisons. *, the significance compared between 2.8 mM and 16.7 mM glucose, #, the significance compared between treatments with and without pharmacological drugs. All statistical tests used were two-sided unless otherwise indicated. **p < 0.01, ***p < 0.001, ****p < 0.0001, ###p < 0.001.