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Intracellular calcium in hypertrophic smooth muscle from rat urinary bladder

Arner, Anders LU ; Scott, Rolf Sjuve; Haase, Hannelore; Morano, Ingo and Uvelius, Bengt LU (2007) In Scandinavian Journal of Urology and Nephrology1967-01-01+01:002013-01-01+01:00 41(4). p.270-277
Abstract
Objective. To explore whether infravesical outlet obstruction is associated with alterations in calcium activation of detrusor smooth muscle. Material and methods. Outlet obstruction was created by partial ligature of the urethra in female rats. Western blotting was performed using an antibody against the cytoplasmatic region of the alpha(1c) subunit of the L- type Ca2(+) channel. Intracellular calcium was measured using Fura-2 in detrusors that had been obstructed for 10 days and activated by high K+ concentrations at different extracellular Ca2(+) concentrations. The rate of force development after rapid opening of L- type Ca2(+) channels was measured in contractions initiated by flash photolysis of nifedipine in Ca2(+) containing... (More)
Objective. To explore whether infravesical outlet obstruction is associated with alterations in calcium activation of detrusor smooth muscle. Material and methods. Outlet obstruction was created by partial ligature of the urethra in female rats. Western blotting was performed using an antibody against the cytoplasmatic region of the alpha(1c) subunit of the L- type Ca2(+) channel. Intracellular calcium was measured using Fura-2 in detrusors that had been obstructed for 10 days and activated by high K+ concentrations at different extracellular Ca2(+) concentrations. The rate of force development after rapid opening of L- type Ca2(+) channels was measured in contractions initiated by flash photolysis of nifedipine in Ca2(+) containing depolarizing solution. Results. Bladder weight increased from 6293 to 254943 mg after 10 days of obstruction. Expression of the alpha(1c) subunit increased after 3 days and continued to increase until it was about fourfold greater after 10 days; however, it had not increased further at 6 weeks. This change was reversible after removal of obstruction. Activation with K+ produced a stable force at different extracellular Ca2(+) concentrations, with no difference in response between controls and rats that had been obstructed for 10 days. Intracellular Ca2(+) concentrations were lower in the obstructed group, showing that the calcium sensitivity of the contraction force had increased. The delay between the opening of L- type channels and the onset of contraction was longer in obstructed detrusors. Conclusions. Growth of detrusor muscle following obstruction is accompanied by attenuated calcium transients following activation, despite upregulation of L- type Ca2(+) channels. The Ca2(+) sensitivity of contraction was increased in obstructed detrusors. We suggest that the decreased surface: volume ratio in hypertrophic smooth muscle cells is partly involved in the lowered Ca2(+) transients. The increases in L- type calcium channels and in calcium sensitivity may be compensatory mechanisms. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
sensitivity, calcium, calcium channels, urinary bladder, urinary outflow obstruction
in
Scandinavian Journal of Urology and Nephrology1967-01-01+01:002013-01-01+01:00
volume
41
issue
4
pages
270 - 277
publisher
Taylor & Francis
external identifiers
  • wos:000249179600002
  • scopus:34548396353
ISSN
0036-5599
DOI
10.1080/00365590701225970
language
English
LU publication?
yes
id
8c3b0c61-66c4-41d1-a86e-1328a3b4d7e3 (old id 688627)
date added to LUP
2007-12-04 15:38:08
date last changed
2017-10-22 04:34:58
@article{8c3b0c61-66c4-41d1-a86e-1328a3b4d7e3,
  abstract     = {Objective. To explore whether infravesical outlet obstruction is associated with alterations in calcium activation of detrusor smooth muscle. Material and methods. Outlet obstruction was created by partial ligature of the urethra in female rats. Western blotting was performed using an antibody against the cytoplasmatic region of the alpha(1c) subunit of the L- type Ca2(+) channel. Intracellular calcium was measured using Fura-2 in detrusors that had been obstructed for 10 days and activated by high K+ concentrations at different extracellular Ca2(+) concentrations. The rate of force development after rapid opening of L- type Ca2(+) channels was measured in contractions initiated by flash photolysis of nifedipine in Ca2(+) containing depolarizing solution. Results. Bladder weight increased from 6293 to 254943 mg after 10 days of obstruction. Expression of the alpha(1c) subunit increased after 3 days and continued to increase until it was about fourfold greater after 10 days; however, it had not increased further at 6 weeks. This change was reversible after removal of obstruction. Activation with K+ produced a stable force at different extracellular Ca2(+) concentrations, with no difference in response between controls and rats that had been obstructed for 10 days. Intracellular Ca2(+) concentrations were lower in the obstructed group, showing that the calcium sensitivity of the contraction force had increased. The delay between the opening of L- type channels and the onset of contraction was longer in obstructed detrusors. Conclusions. Growth of detrusor muscle following obstruction is accompanied by attenuated calcium transients following activation, despite upregulation of L- type Ca2(+) channels. The Ca2(+) sensitivity of contraction was increased in obstructed detrusors. We suggest that the decreased surface: volume ratio in hypertrophic smooth muscle cells is partly involved in the lowered Ca2(+) transients. The increases in L- type calcium channels and in calcium sensitivity may be compensatory mechanisms.},
  author       = {Arner, Anders and Scott, Rolf Sjuve and Haase, Hannelore and Morano, Ingo and Uvelius, Bengt},
  issn         = {0036-5599},
  keyword      = {sensitivity,calcium,calcium channels,urinary bladder,urinary outflow obstruction},
  language     = {eng},
  number       = {4},
  pages        = {270--277},
  publisher    = {Taylor & Francis},
  series       = {Scandinavian Journal of Urology and Nephrology1967-01-01+01:002013-01-01+01:00},
  title        = {Intracellular calcium in hypertrophic smooth muscle from rat urinary bladder},
  url          = {http://dx.doi.org/10.1080/00365590701225970},
  volume       = {41},
  year         = {2007},
}