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On depolarization-evoked exocytosis as a function of calcium entry: possibilities and pitfalls.

Pedersen, Morten Gram LU (2011) In Biophysical Journal 101(4). p.793-802
Abstract
Secretion from many endocrine cells is a result of calcium-regulated exocytosis due to Ca(2+) influx. Using the patch-clamp technique, voltage pulses can be applied to the cells to open Ca(2+) channels, resulting in a measurable Ca(2+) current, and evoke exocytosis, which can be seen as an increase in membrane capacitance. A common tool for evaluating the relation between Ca(2+) influx and exocytosis is to plot the increase in capacitance (ΔC(m)) as a function of the integral of the measured Ca(2+) current (Q). When depolarizations of different lengths are imposed, the rate of exocytosis is typically higher for shorter than for longer pulses, which has been suggested to result from depletion of a granule pool or from Ca(2+) current... (More)
Secretion from many endocrine cells is a result of calcium-regulated exocytosis due to Ca(2+) influx. Using the patch-clamp technique, voltage pulses can be applied to the cells to open Ca(2+) channels, resulting in a measurable Ca(2+) current, and evoke exocytosis, which can be seen as an increase in membrane capacitance. A common tool for evaluating the relation between Ca(2+) influx and exocytosis is to plot the increase in capacitance (ΔC(m)) as a function of the integral of the measured Ca(2+) current (Q). When depolarizations of different lengths are imposed, the rate of exocytosis is typically higher for shorter than for longer pulses, which has been suggested to result from depletion of a granule pool or from Ca(2+) current inactivation. It is here demonstrated that ΔC(m) as a function of Q can reveal whether Ca(2+) current inactivation masquerades as pool depletion. Moreover, it is shown that a convex, cooperativity-like, relation between ΔC(m) and Q surprisingly cannot occur as a result of cooperative effects, but can result from delays in the exocytotic process or in Ca(2+) dynamics. An overview of expected ΔC(m)-versus-Q relations for a range of explicit situations is given, which should help in the interpretation of data of depolarization-evoked exocytosis in endocrine cells. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biophysical Journal
volume
101
issue
4
pages
793 - 802
publisher
Cell Press
external identifiers
  • wos:000294103600008
  • pmid:21843469
  • scopus:80052480935
ISSN
1542-0086
DOI
10.1016/j.bpj.2011.06.061
language
English
LU publication?
yes
id
a8e73cee-81cc-4473-b457-c174a5fe9e75 (old id 2151074)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/21843469?dopt=Abstract
date added to LUP
2011-09-04 22:06:35
date last changed
2017-06-25 03:06:33
@article{a8e73cee-81cc-4473-b457-c174a5fe9e75,
  abstract     = {Secretion from many endocrine cells is a result of calcium-regulated exocytosis due to Ca(2+) influx. Using the patch-clamp technique, voltage pulses can be applied to the cells to open Ca(2+) channels, resulting in a measurable Ca(2+) current, and evoke exocytosis, which can be seen as an increase in membrane capacitance. A common tool for evaluating the relation between Ca(2+) influx and exocytosis is to plot the increase in capacitance (ΔC(m)) as a function of the integral of the measured Ca(2+) current (Q). When depolarizations of different lengths are imposed, the rate of exocytosis is typically higher for shorter than for longer pulses, which has been suggested to result from depletion of a granule pool or from Ca(2+) current inactivation. It is here demonstrated that ΔC(m) as a function of Q can reveal whether Ca(2+) current inactivation masquerades as pool depletion. Moreover, it is shown that a convex, cooperativity-like, relation between ΔC(m) and Q surprisingly cannot occur as a result of cooperative effects, but can result from delays in the exocytotic process or in Ca(2+) dynamics. An overview of expected ΔC(m)-versus-Q relations for a range of explicit situations is given, which should help in the interpretation of data of depolarization-evoked exocytosis in endocrine cells.},
  author       = {Pedersen, Morten Gram},
  issn         = {1542-0086},
  language     = {eng},
  number       = {4},
  pages        = {793--802},
  publisher    = {Cell Press},
  series       = {Biophysical Journal},
  title        = {On depolarization-evoked exocytosis as a function of calcium entry: possibilities and pitfalls.},
  url          = {http://dx.doi.org/10.1016/j.bpj.2011.06.061},
  volume       = {101},
  year         = {2011},
}