Effects of insulin on [Ca2+]c changes in αTC1-9 cells. These panels illustrate the impact of insulin (1.7, 3.4, or 17 nmol/l) on the frequency of [Ca2+]c oscillations at a given concentration of glucose (G; 0, 0.5, 1, or 20 mmol/l). A: Panels show the effects of 3.4 or 17 nmol/l of insulin on [Ca2+]c changes in the absence of glucose. B: Quantification of the experiments above. The dashed line illustrates the frequency of [Ca2+]c oscillations in each experiment, expressed as 100%, before addition of insulin during the first 10 min of perifusion at a
given concentration of glucose, as indicated. The empty bars illustrate control experiments where insulin (ins) was not added,
whereas the light gray, dark gray, and black bars show the effects of 1.7, 3.4, or 17 nmol/l insulin added at 10 min for 10
min. The hatched and crossed bars show the effects of insulin in the presence of 100 nmol/l wortmannin (wt) and IGF-1, respectively.
Values are means ± SE for 11–31 cells from 4 to 9 independent experiments. *P < 0.05 for the effects of insulin.