title: The relationship between membrane potential and calcium dynamics in glucose-stimulated beta cell syncytium in acute mouse pancreas tissue slices.
abstract: Oscillatory electrical activity is regarded as a hallmark of the pancreatic beta cell glucose-dependent excitability pattern. Electrophysiologically recorded membrane potential oscillations in beta cells are associated with in-phase oscillatory cytosolic calcium activity ([Ca(2+)]i) measured with fluorescent probes. Recent high spatial and temporal resolution confocal imaging revealed that glucose stimulation of beta cells in intact islets within acute tissue slices produces a [Ca(2+)]i change with initial transient phase followed by a plateau phase with highly synchronized [Ca(2+)]i oscillations. Here, we aimed to correlate the plateau [Ca(2+)]i oscillations with the oscillations of membrane potential using patch-clamp and for the first time high resolution voltage-sensitive dye based confocal imaging. Our results demonstrated that the glucose-evoked membrane potential oscillations spread over the islet in a wave-like manner, their durations and wave velocities being comparable to the ones for [Ca(2+)]i oscillations and waves. High temporal resolution simultaneous records of membrane potential and [Ca(2+)]i confirmed tight but nevertheless limited coupling of the two processes, with membrane depolarization preceding the [Ca(2+)]i increase. The potassium channel blocker tetraethylammonium increased the velocity at which oscillations advanced over the islet by several-fold while, at the same time, emphasized differences in kinetics of the membrane potential and the [Ca(2+)]i. The combination of both imaging techniques provides a powerful tool that will help us attain deeper knowledge of the beta cell network.
authors: Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia.
authors: Jurij
authors: J
authors: Dolenšek
authors: Andraž
authors: A
authors: Stožer
authors: Maša
authors: M
authors: Skelin Klemen
authors: Evan W
authors: EW
authors: Miller
authors: Marjan
authors: M
authors: Slak Rupnik
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D015726:Giant Cells / Q000378:metabolism; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism*; D007515:Islets of Langerhans / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology*; D051379:Mice; D018613:Microscopy, Confocal; D018408:Patch-Clamp Techniques; D019789:Tetraethylammonium / Q000494:pharmacology
chemical_list: D019789:Tetraethylammonium; D005947:Glucose; D002118:Calcium