FIG. 6.

The ER decreases or increases its [Ca²⁺] to compensate for, respectively, a sustained increase or decrease in [Ca²⁺]_c. [Ca²⁺]_ER (D4ER) was measured in β-cells from SERCA3^+/+ mice. The glucose concentration (G) was increased from 0 to 20 mmol/L before the addition of 250 µmol/L Dz (A) or 1 µmol/L nimodipine (B) or the removal of extracellular Ca²⁺ (Ca0-EGTA) (C). ACh (100 µmol/L) was added at the end of the experiments. Values are means ± SE for 22–42 cells from three experiments with three islet preparations.