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Decreased shortening velocity and altered myosin isoforms in guinea-pig hypertrophic intestinal smooth muscle

Lofgren, Mia; Fagher, Katarina; Karlsson Wede, Oskar LU and Arner, Anders LU (2002) In Journal of Physiology 544(3). p.707-714
Abstract
The aims of this study were to investigate whether hypertrophy of the small intestinal smooth muscle leads to alterations of myosin isoform composition and shortening velocity and whether possible changes correlate with a change in the sensitivity to ADP of shortening velocity in this tissue. A partial occlusion was introduced in the distal part of the ileum of guinea-pigs. After 2 weeks, the part of the small intestine just proximal of the stenosis was hypertrophied (indicated by a significantly increased cross-sectional area). The most proximal part of the small intestine was used as control, thus enabling comparisons between hypertrophic and normal tissue from the same animal. The outer longitudinal layer of the intestinal wall was... (More)
The aims of this study were to investigate whether hypertrophy of the small intestinal smooth muscle leads to alterations of myosin isoform composition and shortening velocity and whether possible changes correlate with a change in the sensitivity to ADP of shortening velocity in this tissue. A partial occlusion was introduced in the distal part of the ileum of guinea-pigs. After 2 weeks, the part of the small intestine just proximal of the stenosis was hypertrophied (indicated by a significantly increased cross-sectional area). The most proximal part of the small intestine was used as control, thus enabling comparisons between hypertrophic and normal tissue from the same animal. The outer longitudinal layer of the intestinal wall was gently peeled off and used for biochemistry, RT-PCR and mechanical experiments. The desmin/actin ratio was significantly increased following hypertrophy, although myosin and actin expression were similar in control and hypertrophic tissue. In hypertrophic tissue, the myosin heavy chain mRNA with a 21 base pair insert decreased significantly. The composition of the mRNA encoding the myosin essential light chains changed towards more of the basic type (LC17b). No change in the expression of non-muscle myosin heavy chains A and B was detected. The maximal shortening velocity (V-max) of maximally activated skinned preparations was significantly lower in the hypertrophic tissue (similar to50% of control). The sensitivity of V-max to ADP was increased in the hypertrophic smooth muscle tissue. We conclude that myosin expression is altered following intestinal hypertrophy and that these alterations affect reactions in the cross-bridge interaction, leading to a slower and more economical contractile function. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physiology
volume
544
issue
3
pages
707 - 714
publisher
The Physiological Society
external identifiers
  • pmid:12411517
  • wos:000179276500005
  • scopus:0036850753
ISSN
1469-7793
DOI
10.1113/jphysiol.2002.027060
language
English
LU publication?
yes
id
df7d17af-8d22-4371-882b-e8bfe6ddc7b0 (old id 323411)
date added to LUP
2007-11-02 09:27:48
date last changed
2017-01-01 06:43:55
@article{df7d17af-8d22-4371-882b-e8bfe6ddc7b0,
  abstract     = {The aims of this study were to investigate whether hypertrophy of the small intestinal smooth muscle leads to alterations of myosin isoform composition and shortening velocity and whether possible changes correlate with a change in the sensitivity to ADP of shortening velocity in this tissue. A partial occlusion was introduced in the distal part of the ileum of guinea-pigs. After 2 weeks, the part of the small intestine just proximal of the stenosis was hypertrophied (indicated by a significantly increased cross-sectional area). The most proximal part of the small intestine was used as control, thus enabling comparisons between hypertrophic and normal tissue from the same animal. The outer longitudinal layer of the intestinal wall was gently peeled off and used for biochemistry, RT-PCR and mechanical experiments. The desmin/actin ratio was significantly increased following hypertrophy, although myosin and actin expression were similar in control and hypertrophic tissue. In hypertrophic tissue, the myosin heavy chain mRNA with a 21 base pair insert decreased significantly. The composition of the mRNA encoding the myosin essential light chains changed towards more of the basic type (LC17b). No change in the expression of non-muscle myosin heavy chains A and B was detected. The maximal shortening velocity (V-max) of maximally activated skinned preparations was significantly lower in the hypertrophic tissue (similar to50% of control). The sensitivity of V-max to ADP was increased in the hypertrophic smooth muscle tissue. We conclude that myosin expression is altered following intestinal hypertrophy and that these alterations affect reactions in the cross-bridge interaction, leading to a slower and more economical contractile function.},
  author       = {Lofgren, Mia and Fagher, Katarina and Karlsson Wede, Oskar and Arner, Anders},
  issn         = {1469-7793},
  language     = {eng},
  number       = {3},
  pages        = {707--714},
  publisher    = {The Physiological Society},
  series       = {Journal of Physiology},
  title        = {Decreased shortening velocity and altered myosin isoforms in guinea-pig hypertrophic intestinal smooth muscle},
  url          = {http://dx.doi.org/10.1113/jphysiol.2002.027060},
  volume       = {544},
  year         = {2002},
}