title: Heterogeneous distribution of exocytotic microdomains in adrenal chromaffin cells resolved by high-density diamond ultra-microelectrode arrays.
abstract: Here we describe the ability of a high-density diamond microelectrode array targeted to resolve multi-site detection of fast exocytotic events from single cells. The array consists of nine boron-doped nanocrystalline diamond ultra-microelectrodes (9-Ch NCD-UMEA) radially distributed within a circular area of the dimensions of a single cell. The device can be operated in voltammetric or chronoamperometric configuration. Sensitivity to catecholamines, tested by dose-response calibrations, set the lowest detectable concentration of adrenaline to ∼5 μm. Catecholamine release from bovine or mouse chromaffin cells could be triggered by electrical stimulation or external KCl-enriched solutions. Spikes detected from the cell apex using carbon fibre microelectrodes showed an excellent correspondence with events measured at the bottom of the cell by the 9-Ch NCD-UMEA, confirming the ability of the array to resolve single quantal secretory events. Subcellular localization of exocytosis was provided by assigning each quantal event to one of the nine channels based on its location. The resulting mapping highlights the heterogeneous distribution of secretory activity in cell microdomains of 12-27 μm2. In bovine chromaffin cells, secretion was highly heterogeneous with zones of high and medium activity in 54% of the cell surface and zones of low or no activity in the remainder. The 'non-active' ('silent') zones covered 24% of the total and persisted for 6-8 min, indicating stable location. The 9-Ch NCD-UMEA therefore appears suitable for investigating the microdomain organization of neurosecretion with high spatial resolution.
authors.affiliation: Department of Drug Science and Technology, NIS Center, University of Turin, 10125, Turin, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Gosso
authors.affiliation: Department of Drug Science and Technology, NIS Center, University of Turin, 10125, Turin, Italy Department of Neuroscience, University of Turin, 10125, Turin, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Turturici
authors.affiliation: Department of Drug Science and Technology, NIS Center, University of Turin, 10125, Turin, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Franchino
authors.affiliation: Department of Drug Science and Technology, NIS Center, University of Turin, 10125, Turin, Italy Institute of Electron Devices and Circuits, University of Ulm, 89069, Ulm, Germany.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Colombo
authors.affiliation: Institute of Electron Devices and Circuits, University of Ulm, 89069, Ulm, Germany.
authors.forename: Alberto
authors.initials: A
authors.lastname: Pasquarelli
authors.affiliation: Department of Drug Science and Technology, NIS Center, University of Turin, 10125, Turin, Italy.
authors.forename: Emilio
authors.initials: E
authors.lastname: Carbone
authors.affiliation: Department of Drug Science and Technology, NIS Center, University of Turin, 10125, Turin, Italy valentina.carabelli@unito.it.
authors.forename: Valentina
authors.initials: V
authors.lastname: Carabelli
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000378:metabolism* / Q000502:physiology; D005089:Exocytosis; D051379:Mice; D008810:Mice, Inbred C57BL; D008839:Microelectrodes; D018408:Patch-Clamp Techniques / Q000295:instrumentation / Q000379:methods*; D046888:Tissue Array Analysis / Q000295:instrumentation / Q000379:methods*