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Gastrin and the neuropeptide PACAP evoke secretion from rat stomach histamine-containing (ECL) cells by stimulating influx of Ca2+ through different Ca2+ channels

Lindström, Erik; Eliasson, Lena LU ; Björkqvist, Maria LU and Håkanson, Rolf LU (2001) In Journal of Physiology 535(3). p.663-677
Abstract
Gastrin and PACAP stimulate secretion of histamine and pancreastatin from isolated rat stomach ECL cells. We have examined whether or not secretion depends on the free cytosolic Ca2+ concentration ([Ca2+i) and the pathways by which gastrin and PACAP elevate [Ca2+i. Secretion was monitored by radioimmunoassay of pancreastatin and changes in [Ca2+i by video imaging. The patch clamp technique was used to record whole-cell currents and membrane capacitance (reflecting exocytosis). In the presence of 2 mM extracellular Ca2+, gastrin and PACAP induced secretion and raised [Ca2+i. Without extracellular Ca2+ (or in the presence of La3+) no secretion occurred. The extracellular Ca2+ concentration required to stimulate secretion was 10 times higher... (More)
Gastrin and PACAP stimulate secretion of histamine and pancreastatin from isolated rat stomach ECL cells. We have examined whether or not secretion depends on the free cytosolic Ca2+ concentration ([Ca2+i) and the pathways by which gastrin and PACAP elevate [Ca2+i. Secretion was monitored by radioimmunoassay of pancreastatin and changes in [Ca2+i by video imaging. The patch clamp technique was used to record whole-cell currents and membrane capacitance (reflecting exocytosis). In the presence of 2 mM extracellular Ca2+, gastrin and PACAP induced secretion and raised [Ca2+i. Without extracellular Ca2+ (or in the presence of La3+) no secretion occurred. The extracellular Ca2+ concentration required to stimulate secretion was 10 times higher for gastrin than for PACAP. Depletion of intracellular Ca2+ pools by thapsigargin had no effect on the capacity of gastrin and PACAP to stimulate secretion. Gastrin-evoked secretion was inhibited 60-80 by L-type channel blockers and 40 by the N-type channel blocker -conotoxin GVIA. Combining L-type and N-type channel blockers did not result in greater inhibition than L-type channel blockers alone. Whole-cell patch clamp measurements confirmed that the ECL cells are equipped with voltage-dependent inward Ca2+ currents. A 500 ms depolarising pulse from -60 mV to +10 mV which maximally opened these channels resulted in an increase in membrane capacitance of 100 fF reflecting exocytosis of secretory vesicles. PACAP-evoked secretion was reduced 40 by L-type channel blockers but was not influenced by inhibition of N-type channels. SKF 96365, a blocker of both L-type and receptor-operated Ca2+ channels, inhibited PACAP-evoked secretion by 85 . Combining L-type channel blockade with SKF 96365 abolished PACAP-evoked secretion. The results indicate that gastrin- and PACAP-evoked secretion depends on Ca2+ entry and not on mobilisation of intracellular Ca2+. While gastrin stimulates secretion via voltage-dependent L-type and N-type Ca2+ channels, PACAP acts via L-type and receptor-operated Ca2+ channels. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
in
Journal of Physiology
volume
535
issue
3
pages
663 - 677
publisher
The Physiological Society
external identifiers
  • wos:000171488300004
  • scopus:0035884554
ISSN
1469-7793
language
English
LU publication?
yes
id
987dee9b-a764-434e-9af5-90dbbece3620 (old id 131229)
alternative location
http://jp.physoc.org/cgi/content/abstract/535/3/663
date added to LUP
2007-07-17 09:13:04
date last changed
2018-04-08 04:25:26
@article{987dee9b-a764-434e-9af5-90dbbece3620,
  abstract     = {Gastrin and PACAP stimulate secretion of histamine and pancreastatin from isolated rat stomach ECL cells. We have examined whether or not secretion depends on the free cytosolic Ca2+ concentration ([Ca2+i) and the pathways by which gastrin and PACAP elevate [Ca2+i. Secretion was monitored by radioimmunoassay of pancreastatin and changes in [Ca2+i by video imaging. The patch clamp technique was used to record whole-cell currents and membrane capacitance (reflecting exocytosis). In the presence of 2 mM extracellular Ca2+, gastrin and PACAP induced secretion and raised [Ca2+i. Without extracellular Ca2+ (or in the presence of La3+) no secretion occurred. The extracellular Ca2+ concentration required to stimulate secretion was 10 times higher for gastrin than for PACAP. Depletion of intracellular Ca2+ pools by thapsigargin had no effect on the capacity of gastrin and PACAP to stimulate secretion. Gastrin-evoked secretion was inhibited 60-80 by L-type channel blockers and 40 by the N-type channel blocker -conotoxin GVIA. Combining L-type and N-type channel blockers did not result in greater inhibition than L-type channel blockers alone. Whole-cell patch clamp measurements confirmed that the ECL cells are equipped with voltage-dependent inward Ca2+ currents. A 500 ms depolarising pulse from -60 mV to +10 mV which maximally opened these channels resulted in an increase in membrane capacitance of 100 fF reflecting exocytosis of secretory vesicles. PACAP-evoked secretion was reduced 40 by L-type channel blockers but was not influenced by inhibition of N-type channels. SKF 96365, a blocker of both L-type and receptor-operated Ca2+ channels, inhibited PACAP-evoked secretion by 85 . Combining L-type channel blockade with SKF 96365 abolished PACAP-evoked secretion. The results indicate that gastrin- and PACAP-evoked secretion depends on Ca2+ entry and not on mobilisation of intracellular Ca2+. While gastrin stimulates secretion via voltage-dependent L-type and N-type Ca2+ channels, PACAP acts via L-type and receptor-operated Ca2+ channels.},
  author       = {Lindström, Erik and Eliasson, Lena and Björkqvist, Maria and Håkanson, Rolf},
  issn         = {1469-7793},
  language     = {eng},
  number       = {3},
  pages        = {663--677},
  publisher    = {The Physiological Society},
  series       = {Journal of Physiology},
  title        = {Gastrin and the neuropeptide PACAP evoke secretion from rat stomach histamine-containing (ECL) cells by stimulating influx of Ca2+ through different Ca2+ channels},
  volume       = {535},
  year         = {2001},
}