Different effects of glucose and potassium depolarization on the granule mobility in the submembrane space of insulin-secreting MIN6 cells

Background and aims: Physiologically, insulin secretion is initiated by an increase in the ambient glucose concentration. This involves a depolarization of the plasma membrane which is experimentally often mimicked by raising the K+ concentration in the medium. It has come into doubt, however, whether the stimulatory effect of a strong K+ depolarization, which produces a first phase-like insulin secretion, is based on the same mechanisms as the first phase of glucose-induced secretion. Methods: Granules in the immediate vicinity of the plasma membrane were visualized by transient transfection of insulin-secretin…