Figure 4.

Calcium-dependent secretion of insulin from control and mutant β cells. Hextuplicate sets of five collagenase-dissociated islets were distributed into reaction vessels and challenged with different Ca²⁺ concentrations as shown. Data are presented as the fraction of total insulin after subtracting basal values from values in 22 mM glucose. Baseline levels of secretion changed very little across the Ca²⁺ titration range. Time point is 60 min.