Modification of the Ca2+ influx pattern of the pancreatic beta cell by high extracellular potassium

Background and aims: K+ depolarization is regarded as an appropriate experimental substitute for the nutrient-induced depolarization of the beta cell plasma membrane and far-reaching conclusions with regard to physiological stimulus-secretion coupling have been based on such experiments. Recently, discrepancies were described that exist between depolarization via KATP channel closure and K+ depolarization. Methods: Mouse pancreatic islets and single beta cells were used to measure insulin secretion, the free cytosolic Ca2+ concentration ([Ca2+]i), membrane potential and membrane currents. Results: Raising the ex…