Insulinotropic effect of high potassium concentration beyond plasma membrane depolarization

Background and aims: In experiments designed to dissect the signalling pathways in beta cells, the depolarizing effect of glucose metabolism is often replaced by a strong K+ depolarization. Recent observations raised doubt that high K+ is an appropriate experimental substitute for the physiologically induced depolarization. Methods: Using mouse islets insulin secretion was measured by batch perifusion and ELISA and the free cytosolic Ca2+ concentration ([Ca2+]i) by the Fura technique. Primary mouse beta cells were used for electrophysiological experiments. Results: At basal glucose 40 mM K+ induced a massive mon…