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Regulated Exocytosis of GABA-containing Synaptic-like Microvesicles in Pancreatic {beta}-cells.

Braun, Matthias; Wendt, Anna LU ; Birnir, Bryndis; Broman, Jonas LU ; Eliasson, Lena; Galvanovskis, Juris; Gromada, Jesper; Mulder, Hindrik LU and Rorsman, Patrik (2004) In Journal of General Physiology 123(3). p.191-204
Abstract
We have explored whether {gamma}-aminobutyric acid (GABA) is released by regulated exocytosis of GABA-containing synaptic-like microvesicles (SLMVs) in insulin-releasing rat pancreatic ß-cells. To this end, ß-cells were engineered to express GABAA-receptor Cl--channels at high density using adenoviral infection. Electron microscopy indicated that the average diameter of the SLMVs is 90 nm, that every ß-cell contains ~3,500 such vesicles, and that insulin-containing large dense core vesicles exclude GABA. Quantal release of GABA, seen as rapidly activating and deactivating Cl--currents, was observed during membrane depolarizations from -70 mV to voltages beyond -40 mV or when Ca2+ was dialysed into the cell interior. Depolarization-evoked... (More)
We have explored whether {gamma}-aminobutyric acid (GABA) is released by regulated exocytosis of GABA-containing synaptic-like microvesicles (SLMVs) in insulin-releasing rat pancreatic ß-cells. To this end, ß-cells were engineered to express GABAA-receptor Cl--channels at high density using adenoviral infection. Electron microscopy indicated that the average diameter of the SLMVs is 90 nm, that every ß-cell contains ~3,500 such vesicles, and that insulin-containing large dense core vesicles exclude GABA. Quantal release of GABA, seen as rapidly activating and deactivating Cl--currents, was observed during membrane depolarizations from -70 mV to voltages beyond -40 mV or when Ca2+ was dialysed into the cell interior. Depolarization-evoked GABA release was suppressed when Ca2+ entry was inhibited using Cd2+. Analysis of the kinetics of GABA release revealed that GABA-containing vesicles can be divided into a readily releasable pool and a reserve pool. Simultaneous measurements of GABA release and cell capacitance indicated that exocytosis of SLMVs contributes ~1% of the capacitance signal. Mathematical analysis of the release events suggests that every SLMV contains 0.36 amol of GABA. We conclude that there are two parallel pathways of exocytosis in pancreatic ß-cells and that release of GABA may accordingly be temporally and spatially separated from insulin secretion. This provides a basis for paracrine GABAergic signaling within the islet. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
GABA, GAD65, pancreatic islets, paracrine communication, SLMV
in
Journal of General Physiology
volume
123
issue
3
pages
191 - 204
publisher
Rockefeller Institute for Medical Research
external identifiers
  • wos:000220024500002
  • pmid:14769845
  • scopus:1442358665
ISSN
0022-1295
DOI
10.1085/jgp.200308966
language
English
LU publication?
yes
id
addc0ee0-7ee8-4979-8b11-7d565f7f03f9 (old id 120644)
date added to LUP
2007-07-10 14:50:56
date last changed
2017-10-01 04:48:10
@article{addc0ee0-7ee8-4979-8b11-7d565f7f03f9,
  abstract     = {We have explored whether {gamma}-aminobutyric acid (GABA) is released by regulated exocytosis of GABA-containing synaptic-like microvesicles (SLMVs) in insulin-releasing rat pancreatic ß-cells. To this end, ß-cells were engineered to express GABAA-receptor Cl--channels at high density using adenoviral infection. Electron microscopy indicated that the average diameter of the SLMVs is 90 nm, that every ß-cell contains ~3,500 such vesicles, and that insulin-containing large dense core vesicles exclude GABA. Quantal release of GABA, seen as rapidly activating and deactivating Cl--currents, was observed during membrane depolarizations from -70 mV to voltages beyond -40 mV or when Ca2+ was dialysed into the cell interior. Depolarization-evoked GABA release was suppressed when Ca2+ entry was inhibited using Cd2+. Analysis of the kinetics of GABA release revealed that GABA-containing vesicles can be divided into a readily releasable pool and a reserve pool. Simultaneous measurements of GABA release and cell capacitance indicated that exocytosis of SLMVs contributes ~1% of the capacitance signal. Mathematical analysis of the release events suggests that every SLMV contains 0.36 amol of GABA. We conclude that there are two parallel pathways of exocytosis in pancreatic ß-cells and that release of GABA may accordingly be temporally and spatially separated from insulin secretion. This provides a basis for paracrine GABAergic signaling within the islet.},
  author       = {Braun, Matthias and Wendt, Anna and Birnir, Bryndis and Broman, Jonas and Eliasson, Lena and Galvanovskis, Juris and Gromada, Jesper and Mulder, Hindrik and Rorsman, Patrik},
  issn         = {0022-1295},
  keyword      = {GABA,GAD65,pancreatic islets,paracrine communication,SLMV},
  language     = {eng},
  number       = {3},
  pages        = {191--204},
  publisher    = {Rockefeller Institute for Medical Research},
  series       = {Journal of General Physiology},
  title        = {Regulated Exocytosis of GABA-containing Synaptic-like Microvesicles in Pancreatic {beta}-cells.},
  url          = {http://dx.doi.org/10.1085/jgp.200308966},
  volume       = {123},
  year         = {2004},
}