Effect of ZnCl2 and insulin on [Ca2+]c oscillations in αTC1-9 cells (A–C) and mouse α-cells (D). A: Frequency of [Ca2+]c oscillations in the absence (○) or in the presence (•) of insulin at a given concentration of glucose in αTC1-9 cells. B: After 10 min of perifusion, 0.7 nmol/l ZnCl2 was applied. C: The quantification of experiments similar to those performed in B. Cells were perifused for 10 min in 0 or 20 mmol/l glucose, in the presence or in the absence of insulin, as indicated. After
10 min, 30 μmol/l of ZnCl2 was added. The dashed line illustrates [Ca2+]c oscillation frequency, expressed as 100%, under basal conditions during the first 10 min of perifusion, and bars illustrate
the frequency after the addition of ZnCl2. D: [Ca2+]c changes in primary mouse α-cells within a cluster of four cells, with 17 nmol/l and 30 μmol/l ZnCl2 applied as indicated. Values are means ± SE for 11–29 cells from 4 to 9 independent experiments. *P < 0.05 for the effects of insulin or ZnCl2. G, glucose.