No evidence for a role of reverse Na+-Ca2+ exchange in insulin release from mouse pancreatic islets

The role of calcium (Ca2+) currents in the initiation of insulin secretion in intact mouse pancreatic islets is investigated based on measurements of insulin release, cytoplasmic calcium concentration and B cell membrane potential. Data indicate that Ca2+ influx via reverse Na+-Ca2+ exchange has no effect on cytoplasmic calcium concentration. However, Ca2+ influx via voltage-dependent Ca2+ channels promote insulin release by increasing cytoplasmic calcium levels through removal of Na+.