title: Membrane Potential and Calcium Dynamics in Beta Cells from Mouse Pancreas Tissue Slices: Theory, Experimentation, and Analysis.
abstract: Beta cells in the pancreatic islets of Langerhans are precise biological sensors for glucose and play a central role in balancing the organism between catabolic and anabolic needs. A hallmark of the beta cell response to glucose are oscillatory changes of membrane potential that are tightly coupled with oscillatory changes in intracellular calcium concentration which, in turn, elicit oscillations of insulin secretion. Both membrane potential and calcium changes spread from one beta cell to the other in a wave-like manner. In order to assess the properties of the abovementioned responses to physiological and pathological stimuli, the main challenge remains how to effectively measure membrane potential and calcium changes at the same time with high spatial and temporal resolution, and also in as many cells as possible. To date, the most wide-spread approach has employed the electrophysiological patch-clamp method to monitor membrane potential changes. Inherently, this technique has many advantages, such as a direct contact with the cell and a high temporal resolution. However, it allows one to assess information from a single cell only. In some instances, this technique has been used in conjunction with CCD camera-based imaging, offering the opportunity to simultaneously monitor membrane potential and calcium changes, but not in the same cells and not with a reliable cellular or subcellular spatial resolution. Recently, a novel family of highly-sensitive membrane potential reporter dyes in combination with high temporal and spatial confocal calcium imaging allows for simultaneously detecting membrane potential and calcium changes in many cells at a time. Since the signals yielded from both types of reporter dyes are inherently noisy, we have developed complex methods of data denoising that permit for visualization and pixel-wise analysis of signals. Combining the experimental approach of high-resolution imaging with the advanced analysis of noisy data enables novel physiological insights and reassessment of current concepts in unprecedented detail.
authors.affiliation: Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia. jurij.dolensek@um.si.
authors.forename: Jurij
authors.initials: J
authors.lastname: Dolenšek
authors.affiliation: Faculty of Electrical Engineering and Computer Science, University of Maribor, SI-2000 Maribor, Slovenia.
authors.forename: Denis
authors.initials: D
authors.lastname: Špelič
authors.affiliation: Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia. masa.skelin@um.si.
authors.forename: Maša Skelin
authors.initials: MS
authors.lastname: Klemen
authors.affiliation: Faculty of Electrical Engineering and Computer Science, University of Maribor, SI-2000 Maribor, Slovenia.|Center for Open Innovation and Research, Core@UM, University of Maribor, SI-2000 Maribor, Slovenia.
authors.forename: Borut
authors.initials: B
authors.lastname: Žalik
authors.affiliation: Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia. marko.gosak@um.si.|Center for Open Innovation and Research, Core@UM, University of Maribor, SI-2000 Maribor, Slovenia. marko.gosak@um.si.|Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia. marko.gosak@um.si.
authors.forename: Marko
authors.initials: M
authors.lastname: Gosak
authors.affiliation: Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia. marjan.rupnik@um.si.|Center for Open Innovation and Research, Core@UM, University of Maribor, SI-2000 Maribor, Slovenia. marjan.rupnik@um.si.|Center for Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria. marjan.rupnik@um.si.
authors.forename: Marjan Slak
authors.initials: MS
authors.lastname: Rupnik
authors.affiliation: Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia. andraz.stozer@um.si.|Center for Open Innovation and Research, Core@UM, University of Maribor, SI-2000 Maribor, Slovenia. andraz.stozer@um.si.
authors.forename: Andraž
authors.initials: A
authors.lastname: Stožer
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D007515:Islets of Langerhans / Q000166:cytology* / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology*; D051379:Mice; D008954:Models, Biological; D061848:Optical Imaging
chemical_list: D002118:Calcium
keywords: beta cell; calcium imaging; calcium sensors; denoising; membrane potential imaging; membrane potential sensors; pancreas; patch-clamp