Insulin granule mobility, cytosolic calcium concentration, and stimulated insulin secretion in MIN6 cells and beta cells: differences and similarities

Background and aims: The conventional view that insulin granules are sequentially recruited to release insulin has been superseded by newer, more complex models, resulting from TIRF imaging. Here, we compared insulin secretion, cytosolic Ca2+ concentration ([Ca2+]i) and granule mobility in MIN6 cells and in primary mouse beta cells. Methods: Insulin secretion was measured in perifused MIN6 pseudo-islets or cultured mouse islets. [Ca2+]i was measured by the Fura technique, granule mobility (insulin-EGFP-label) was imaged by TIRF microscopy. In these experiments the temperature was 32 °C. Results: With both cell t…