Figure 3. Effects of different exogenous Ca²⁺ chelators on isolated islet cell glucose-induced insulin release.

Islet cells were loaded for 1 h at 37 °C in modified Krebs buffer with 100 μmol l⁻¹ of the different exogenous chelators in AM form. Then, 1 × 10⁵ islet cells were perifused at a flow rate of 1 ml min⁻¹ at 37 °C with fresh modified Krebs buffer supplemented with 1 % bovine serum albumin. After a 30 min stabilization period with 3 mmol l⁻¹ glucose, the islet cells were perifused for 10 min with 3 mmol l⁻¹ glucose, then for 20 min with 22.2 mmol l⁻¹ glucose and finally for 10 min with 3 mmol l⁻¹ glucose. A, unloaded control islet cells. B, 100 μmol l⁻¹ EGTA-loaded islet cells. C, 100 μmol l⁻¹ BAPTA-loaded islet cells. Insulin was assayed by radioimmunoassay and determinations were run in triplicate. Values are expressed as means ±s.e.m. of 4 experiments. Bars represent the addition of the different glucose concentrations.