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Kinetics of contraction in depolarized smooth muscle from guinea-pig taenia coli after photodestruction of nifedipine

Malmqvist, Ulf LU and Arner, Anders LU (1999) In Journal of Physiology 519(1). p.213-221
Abstract
1. The time course and kinetics of force development following activation by opening of L-type Ca2+ channels was investigated using photodestruction of the Ca2+ channel blocker nifedipine in smooth muscle from the guinea-pig taenia coli. 2. In muscles activated using high K+ and Ca2+ and subsequently inhibited with nifedipine, photodestruction of the drug using a strong ultraviolet light flash initiated a rapid contraction. The force initiated by photodestruction of nifedipine reached near-maximal levels. This procedure eliminates diffusional delays and can thus be used to investigate the kinetics of depolarization-induced contractions. 3. The rate of force development of contractions initiated by photodestruction of nifedipine was slower... (More)
1. The time course and kinetics of force development following activation by opening of L-type Ca2+ channels was investigated using photodestruction of the Ca2+ channel blocker nifedipine in smooth muscle from the guinea-pig taenia coli. 2. In muscles activated using high K+ and Ca2+ and subsequently inhibited with nifedipine, photodestruction of the drug using a strong ultraviolet light flash initiated a rapid contraction. The force initiated by photodestruction of nifedipine reached near-maximal levels. This procedure eliminates diffusional delays and can thus be used to investigate the kinetics of depolarization-induced contractions. 3. The rate of force development of contractions initiated by photodestruction of nifedipine was slower than that observed in maximally thiophosphorylated skinned fibres. This suggests the rate of force development is limited by activation steps in the activation cascade prior to the force generation of the cross-bridge system. 4. The rate of force development and the plateau force were dependent on the extracellular [CaCl2] suggesting that the intracellular [Ca2+] determines the rate of phosphorylation and force development. The delay between illumination and increase in force was about 300 ms. The delay was similar at low and high extracellular [CaCl2] indicating that buffering by superficial sarcoplasmatic reticulum does not introduce a delay in force development following activation of Ca2+ channels in this muscle. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physiology
volume
519
issue
1
pages
213 - 221
publisher
The Physiological Society
external identifiers
  • pmid:10432352
  • scopus:0033567171
ISSN
1469-7793
language
English
LU publication?
yes
id
3bafd2a1-9a82-461a-a2b9-252b5aa39b9d (old id 1115783)
alternative location
http://jp.physoc.org/cgi/content/full/519/1/213
date added to LUP
2008-07-08 14:15:41
date last changed
2017-01-01 06:40:10
@article{3bafd2a1-9a82-461a-a2b9-252b5aa39b9d,
  abstract     = {1. The time course and kinetics of force development following activation by opening of L-type Ca2+ channels was investigated using photodestruction of the Ca2+ channel blocker nifedipine in smooth muscle from the guinea-pig taenia coli. 2. In muscles activated using high K+ and Ca2+ and subsequently inhibited with nifedipine, photodestruction of the drug using a strong ultraviolet light flash initiated a rapid contraction. The force initiated by photodestruction of nifedipine reached near-maximal levels. This procedure eliminates diffusional delays and can thus be used to investigate the kinetics of depolarization-induced contractions. 3. The rate of force development of contractions initiated by photodestruction of nifedipine was slower than that observed in maximally thiophosphorylated skinned fibres. This suggests the rate of force development is limited by activation steps in the activation cascade prior to the force generation of the cross-bridge system. 4. The rate of force development and the plateau force were dependent on the extracellular [CaCl2] suggesting that the intracellular [Ca2+] determines the rate of phosphorylation and force development. The delay between illumination and increase in force was about 300 ms. The delay was similar at low and high extracellular [CaCl2] indicating that buffering by superficial sarcoplasmatic reticulum does not introduce a delay in force development following activation of Ca2+ channels in this muscle.},
  author       = {Malmqvist, Ulf and Arner, Anders},
  issn         = {1469-7793},
  language     = {eng},
  number       = {1},
  pages        = {213--221},
  publisher    = {The Physiological Society},
  series       = {Journal of Physiology},
  title        = {Kinetics of contraction in depolarized smooth muscle from guinea-pig taenia coli after photodestruction of nifedipine},
  volume       = {519},
  year         = {1999},
}