FIGURE 6.

Islet cells isolated from BALB/c mice were incubated with 0, 1, 10, or 100 nmol/L, or 1 μM trametinib for 24 h. (A) Representative fluorescence microscopy images are shown for each concentration. Islet cells were stained with Calcein-AM (green: viable cells) and PI (red: dead cells). Original magnification, ×40; scale bar: 100 μm. (B) Percentage of viable islet cells in the presence of the indicated concentration of trametinib, calculated from an average of 40 islets (n = 5/group). (C) Total insulin content per islet after 24 h culture in the presence of each concentration of trametinib (n = 4/group). (D) Concentration of insulin detected in the presence of low (3.3 mmol/L) and high (20 mmol/L) glucose after 24 h of culture with the indicated concentrations of trametinib. (E) The stimulation index was calculated for each group (n = 4/group) by dividing the value for insulin secretion at high-glucose concentration by that at low-glucose concentration. Data are representative of 5 independent experiments (mean ± SD; 1-way ANOVA followed by the Tukey-Kramer test). PI, propidium iodide.