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Calcium sensitivity and energetics of contraction in skinned smooth muscle of the guinea pig taenia coli at altered pH

Arheden, Håkan LU ; Arner, Anders LU and Hellstrand, Per LU (1989) In Pflügers Archiv 413(5). p.476-481
Abstract
Calcium-sensitivity of contraction, force-velocity relation and ATP hydrolysis rate at different pH (6.2-7.8) were investigated in skinned smooth muscle preparations from the guinea pig taenia coli. Varied free-calcium levels were buffered by 4 mM BAPTA (1,2-bis(2-aminophenoxy)-ethane-N,N,N'N'-tetraacetic acid) which has calcium binding properties little affected by pH. A small increase of calcium-sensitivity of contraction was seen at pH 6.2 compared to 6.9 and 7.8 (ED50 shift of about 0.15 pCa units). The isometric force and Vmax in fibres activated either by calcium or by thiophosphorylation of the myosin light chains were each reduced by about 15% at pH 6.2 compared to 6.9 and 7.8. Following an isotonic quick release the shortening... (More)
Calcium-sensitivity of contraction, force-velocity relation and ATP hydrolysis rate at different pH (6.2-7.8) were investigated in skinned smooth muscle preparations from the guinea pig taenia coli. Varied free-calcium levels were buffered by 4 mM BAPTA (1,2-bis(2-aminophenoxy)-ethane-N,N,N'N'-tetraacetic acid) which has calcium binding properties little affected by pH. A small increase of calcium-sensitivity of contraction was seen at pH 6.2 compared to 6.9 and 7.8 (ED50 shift of about 0.15 pCa units). The isometric force and Vmax in fibres activated either by calcium or by thiophosphorylation of the myosin light chains were each reduced by about 15% at pH 6.2 compared to 6.9 and 7.8. Following an isotonic quick release the shortening velocity decreases with time. This effect was more pronounced at pH 6.2 than at pH 6.9 or 7.8. The ATP hydrolysis rates in relaxed and thiophosphorylated fibres were essentially unaffected by alteration in pH between 6.2 and 7.8. Due to the lower force, energetic cost of force maintenance was thus somewhat increased at pH 6.2. These results suggest that pH alteration between 6.2 and 7.8 have effects on the properties of the contractile machinery of the smooth muscle in the skinned guinea pig taenia coli. The effects are however small and therefore probably of little functional importance over a pH range which should cover most cases of intracellular pH alteration under physiological or pathophysiological conditions. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Calcium sensitivity, Calmodulin, BAPTA, pH, Muscle energetics, Muscle mechanics, Skinned smooth muscle
in
Pflügers Archiv
volume
413
issue
5
pages
476 - 481
publisher
Springer
external identifiers
  • pmid:2500640
  • scopus:0024506653
ISSN
0031-6768
DOI
10.1007/BF00594176
language
English
LU publication?
yes
id
be461b5a-a69b-4ca5-88d8-492733ce47f0 (old id 1104635)
date added to LUP
2008-08-06 12:09:33
date last changed
2017-01-01 07:10:16
@article{be461b5a-a69b-4ca5-88d8-492733ce47f0,
  abstract     = {Calcium-sensitivity of contraction, force-velocity relation and ATP hydrolysis rate at different pH (6.2-7.8) were investigated in skinned smooth muscle preparations from the guinea pig taenia coli. Varied free-calcium levels were buffered by 4 mM BAPTA (1,2-bis(2-aminophenoxy)-ethane-N,N,N'N'-tetraacetic acid) which has calcium binding properties little affected by pH. A small increase of calcium-sensitivity of contraction was seen at pH 6.2 compared to 6.9 and 7.8 (ED50 shift of about 0.15 pCa units). The isometric force and Vmax in fibres activated either by calcium or by thiophosphorylation of the myosin light chains were each reduced by about 15% at pH 6.2 compared to 6.9 and 7.8. Following an isotonic quick release the shortening velocity decreases with time. This effect was more pronounced at pH 6.2 than at pH 6.9 or 7.8. The ATP hydrolysis rates in relaxed and thiophosphorylated fibres were essentially unaffected by alteration in pH between 6.2 and 7.8. Due to the lower force, energetic cost of force maintenance was thus somewhat increased at pH 6.2. These results suggest that pH alteration between 6.2 and 7.8 have effects on the properties of the contractile machinery of the smooth muscle in the skinned guinea pig taenia coli. The effects are however small and therefore probably of little functional importance over a pH range which should cover most cases of intracellular pH alteration under physiological or pathophysiological conditions.},
  author       = {Arheden, Håkan and Arner, Anders and Hellstrand, Per},
  issn         = {0031-6768},
  keyword      = {Calcium sensitivity,Calmodulin,BAPTA,pH,Muscle energetics,Muscle mechanics,Skinned smooth muscle},
  language     = {eng},
  number       = {5},
  pages        = {476--481},
  publisher    = {Springer},
  series       = {Pflügers Archiv},
  title        = {Calcium sensitivity and energetics of contraction in skinned smooth muscle of the guinea pig taenia coli at altered pH},
  url          = {http://dx.doi.org/10.1007/BF00594176},
  volume       = {413},
  year         = {1989},
}