Advanced

Corelease and differential exit via the fusion pore of GABA, serotonin, and ATP from LDCV in rat pancreatic beta cells

Braun, Matthias LU ; Wendt, Anna LU ; Karanauskaite, Jovita LU ; Galvanovskis, Juris LU ; Clark, Anne; MacDonald, Patrick LU and Rorsman, Patrik LU (2007) In Journal of General Physiology 129(3). p.221-231
Abstract
The release gamma-aminobutyric acid (GABA) and ATP from rat beta cells was monitored using an electrophysiological assay based on overexpression GABAA or P2X2 receptor ion channels. Exocytosis of LDCVs, detected by carbon fiber amperometry of serotonin, correlated strongly (similar to 80%) with ATP release. The increase in membrane capacitance per ATP release event was 3.4 fF, close to the expected capacitance of an individual LDCV with a diameter of 0.3 mu m. ATP and GABA were coreleased with serotonin with the same probability. Immunogold electron microscopy revealed that similar to 15% of the LDCVs contain GABA. Prespike "pedestals," reflecting exit of granule constituents via the fusion pore, were less frequently observed for ATP than... (More)
The release gamma-aminobutyric acid (GABA) and ATP from rat beta cells was monitored using an electrophysiological assay based on overexpression GABAA or P2X2 receptor ion channels. Exocytosis of LDCVs, detected by carbon fiber amperometry of serotonin, correlated strongly (similar to 80%) with ATP release. The increase in membrane capacitance per ATP release event was 3.4 fF, close to the expected capacitance of an individual LDCV with a diameter of 0.3 mu m. ATP and GABA were coreleased with serotonin with the same probability. Immunogold electron microscopy revealed that similar to 15% of the LDCVs contain GABA. Prespike "pedestals," reflecting exit of granule constituents via the fusion pore, were less frequently observed for ATP than for serotonin or GABA and the relative amplitude (amplitude of foot compared to spike) was smaller: in some cases the ATP-dependent pedestal was missing entirely. An inward tonic current, not dependent on glucose and inhibited by the GABAA receptor antagonist SR95531, was observed in beta cells in clusters of islet cells. Noise analysis indicated that it was due to the activity of individual channels with a conductance of 30 pS, the same as expected for individual GABA(A) Cl- channels with the ionic gradients used. We conclude that (a) LDCVs accumulate ATP and serotonin; (b) regulated release of GABA can be accounted for by exocytosis of a subset of insulin-containing LDCVs; (c) the fusion pore of LDCVs exhibits selectivity and compounds are differentially released depending on their chemical properties (including size); and (d) a glucose-independent nonvesicular form of GABA release exists in beta cells. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of General Physiology
volume
129
issue
3
pages
221 - 231
publisher
Rockefeller Institute for Medical Research
external identifiers
  • wos:000244484600003
  • scopus:33847342070
ISSN
0022-1295
DOI
10.1085/jgp.200609658
language
English
LU publication?
yes
id
8dcd3221-4bc0-450e-94c3-29cbb496ff8e (old id 673697)
date added to LUP
2007-12-11 15:49:05
date last changed
2017-06-25 04:28:35
@article{8dcd3221-4bc0-450e-94c3-29cbb496ff8e,
  abstract     = {The release gamma-aminobutyric acid (GABA) and ATP from rat beta cells was monitored using an electrophysiological assay based on overexpression GABAA or P2X2 receptor ion channels. Exocytosis of LDCVs, detected by carbon fiber amperometry of serotonin, correlated strongly (similar to 80%) with ATP release. The increase in membrane capacitance per ATP release event was 3.4 fF, close to the expected capacitance of an individual LDCV with a diameter of 0.3 mu m. ATP and GABA were coreleased with serotonin with the same probability. Immunogold electron microscopy revealed that similar to 15% of the LDCVs contain GABA. Prespike "pedestals," reflecting exit of granule constituents via the fusion pore, were less frequently observed for ATP than for serotonin or GABA and the relative amplitude (amplitude of foot compared to spike) was smaller: in some cases the ATP-dependent pedestal was missing entirely. An inward tonic current, not dependent on glucose and inhibited by the GABAA receptor antagonist SR95531, was observed in beta cells in clusters of islet cells. Noise analysis indicated that it was due to the activity of individual channels with a conductance of 30 pS, the same as expected for individual GABA(A) Cl- channels with the ionic gradients used. We conclude that (a) LDCVs accumulate ATP and serotonin; (b) regulated release of GABA can be accounted for by exocytosis of a subset of insulin-containing LDCVs; (c) the fusion pore of LDCVs exhibits selectivity and compounds are differentially released depending on their chemical properties (including size); and (d) a glucose-independent nonvesicular form of GABA release exists in beta cells.},
  author       = {Braun, Matthias and Wendt, Anna and Karanauskaite, Jovita and Galvanovskis, Juris and Clark, Anne and MacDonald, Patrick and Rorsman, Patrik},
  issn         = {0022-1295},
  language     = {eng},
  number       = {3},
  pages        = {221--231},
  publisher    = {Rockefeller Institute for Medical Research},
  series       = {Journal of General Physiology},
  title        = {Corelease and differential exit via the fusion pore of GABA, serotonin, and ATP from LDCV in rat pancreatic beta cells},
  url          = {http://dx.doi.org/10.1085/jgp.200609658},
  volume       = {129},
  year         = {2007},
}