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

Background and aims: TIRF microscopy has changed our view on insulin granule behaviour. Here, we characterized the number and mobility of submembrane granules when insulinotropic stimuli were applied at physiological and sub-physiological temperatures. Methods: Submembrane granules of MIN6 cells were labeled by insulin-EGFP and imaged by TIRF microscopy. The cells were perifused with Krebs-Ringer medium at 37 °C, 32 °C or 22 °C. Image sequences (1 sequence = 200 images = 25 seconds) were taken at 8 time points during one experiment and evaluated by an in-house written program. Results: Under control conditions (…