FIGURE 9.

Sulfonylureas and high K⁺ induce insulin but not IGF2 secretion. MIN6 cells were incubated for the indicated periods of time with 3 mm glucose and in the presence of tolbutamide (A) or 30 mm KCl (B). Secreted IGF2 and insulin were then determined. Secretion is calculated as percent of intracellular content and reported in the figure as fold increase over basal (3 mm). Tolbutamide and KCl increase insulin but not IGF2 secretion, in agreement with the high intracellular store of insulin and the requirement of stimulated biosynthesis, and low intracellular IGF2 pools. The data are the means ± S.D. from three independent experiments. **, p < 0.01; ***, p < 0.001.