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Fast insulin secretion reflects exocytosis of docked granules in mouse pancreatic B-cells.

Olofsson, Charlotta LU ; Göpel, Sven LU ; Barg, Sebastian LU ; Galvanovskis, Juris LU ; Ma, Xiaosong LU ; Salehi, Albert; Rorsman, Patrik LU and Eliasson, Lena LU (2002) In Pflügers Archiv 444(1-2). p.43-51
Abstract
A readily releasable pool (RRP) of granules has been proposed to underlie the first phase of insulin secretion. In the present study we combined electron microscopy, insulin secretion measurements and recordings of cell capacitance in an attempt to define this pool ultrastructurally. Mouse pancreatic B-cells contain approximately 9,000 granules, of which 7% are docked below the plasma membrane. The number of docked granules was reduced by 30% (200 granules) during 10 min stimulation with high K+. This stimulus depolarized the cell to -10 mV, elevated cytosolic [Ca2+] ([Ca2+](i)) from a basal concentration of 130 nM to a peak of 1.3 microM and released 0.5 ng insulin/islet, corresponding to 200-300 granules/cell. The Ca2+ transient decayed... (More)
A readily releasable pool (RRP) of granules has been proposed to underlie the first phase of insulin secretion. In the present study we combined electron microscopy, insulin secretion measurements and recordings of cell capacitance in an attempt to define this pool ultrastructurally. Mouse pancreatic B-cells contain approximately 9,000 granules, of which 7% are docked below the plasma membrane. The number of docked granules was reduced by 30% (200 granules) during 10 min stimulation with high K+. This stimulus depolarized the cell to -10 mV, elevated cytosolic [Ca2+] ([Ca2+](i)) from a basal concentration of 130 nM to a peak of 1.3 microM and released 0.5 ng insulin/islet, corresponding to 200-300 granules/cell. The Ca2+ transient decayed towards the prestimulatory concentration within approximately 200 s, presumably reflecting Ca2+ channel inactivation. Renewed stimulation with high K+ failed to stimulate insulin secretion when applied in the absence of glucose. The size of the RRP, derived from the insulin measurements, is similar to that estimated from the increase in cell capacitance elicited by photolytic release of caged Ca2+. We propose that the RRP represents a subset of the docked pool of granules and that replenishment of RRP can be accounted for largely by chemical modification of granules already in place or situated close to the plasma membrane. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Pflügers Archiv
volume
444
issue
1-2
pages
43 - 51
publisher
Springer
external identifiers
  • pmid:11976915
  • wos:000175781400004
  • scopus:0036261251
ISSN
0031-6768
DOI
10.1007/s00424-002-0781-5
language
English
LU publication?
yes
id
e8eb3242-f247-4213-8366-6272690c9602 (old id 107824)
alternative location
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11976915&dopt=Abstract
date added to LUP
2007-07-18 14:02:07
date last changed
2017-09-17 06:59:31
@article{e8eb3242-f247-4213-8366-6272690c9602,
  abstract     = {A readily releasable pool (RRP) of granules has been proposed to underlie the first phase of insulin secretion. In the present study we combined electron microscopy, insulin secretion measurements and recordings of cell capacitance in an attempt to define this pool ultrastructurally. Mouse pancreatic B-cells contain approximately 9,000 granules, of which 7% are docked below the plasma membrane. The number of docked granules was reduced by 30% (200 granules) during 10 min stimulation with high K+. This stimulus depolarized the cell to -10 mV, elevated cytosolic [Ca2+] ([Ca2+](i)) from a basal concentration of 130 nM to a peak of 1.3 microM and released 0.5 ng insulin/islet, corresponding to 200-300 granules/cell. The Ca2+ transient decayed towards the prestimulatory concentration within approximately 200 s, presumably reflecting Ca2+ channel inactivation. Renewed stimulation with high K+ failed to stimulate insulin secretion when applied in the absence of glucose. The size of the RRP, derived from the insulin measurements, is similar to that estimated from the increase in cell capacitance elicited by photolytic release of caged Ca2+. We propose that the RRP represents a subset of the docked pool of granules and that replenishment of RRP can be accounted for largely by chemical modification of granules already in place or situated close to the plasma membrane.},
  author       = {Olofsson, Charlotta and Göpel, Sven and Barg, Sebastian and Galvanovskis, Juris and Ma, Xiaosong and Salehi, Albert and Rorsman, Patrik and Eliasson, Lena},
  issn         = {0031-6768},
  language     = {eng},
  number       = {1-2},
  pages        = {43--51},
  publisher    = {Springer},
  series       = {Pflügers Archiv},
  title        = {Fast insulin secretion reflects exocytosis of docked granules in mouse pancreatic B-cells.},
  url          = {http://dx.doi.org/10.1007/s00424-002-0781-5},
  volume       = {444},
  year         = {2002},
}