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Effects of thyroxine on myosin isoform expression and mechanical properties in guinea-pig smooth muscle.

Löfgren, Mia; Fagher, Katarina; Woodard, Geoffrey and Arner, Anders LU (2002) In Journal of Physiology 543(3). p.757-766
Abstract
Information on the effects of thyroid hormone on smooth muscle contractile protein expression and mechanical properties is sparse. We have addressed the following questions. (1) Can thyroxine hormone alter myosin isoform composition in smooth muscle? (2) Can a change in myosin isoform composition lead to altered mechanical properties in smooth muscle? (3) Are alterations, if occurring, equal in fast and slow smooth muscle types? Guinea-pigs were treated with thyroxine (T(4)) for 12 days. Control animals were given physiological saline solution. Maximal unloaded shortening velocity (V(max)) was measured in chemically skinned, maximally activated muscle preparations from the aorta and the taenia coli. V(max) increased following thyroxine... (More)
Information on the effects of thyroid hormone on smooth muscle contractile protein expression and mechanical properties is sparse. We have addressed the following questions. (1) Can thyroxine hormone alter myosin isoform composition in smooth muscle? (2) Can a change in myosin isoform composition lead to altered mechanical properties in smooth muscle? (3) Are alterations, if occurring, equal in fast and slow smooth muscle types? Guinea-pigs were treated with thyroxine (T(4)) for 12 days. Control animals were given physiological saline solution. Maximal unloaded shortening velocity (V(max)) was measured in chemically skinned, maximally activated muscle preparations from the aorta and the taenia coli. V(max) increased following thyroxine treatment, by approximately 20 % in the taenia coli. In the aorta, no significant increase in V(max) could be detected. The sensitivity of isometric force to inorganic phosphate (P(i)) was increased in the taenia coli following thyroxine treatment. The expression of mRNA (determined with RT-PCR) for the myosin heavy chain with the seven amino acid insert increased by approximately 70 % in the aorta and about 25 % in the taenia coli following thyroxine treatment. Western blot analysis showed an increase in the inserted myosin heavy chain form in the taenia coli. Expression of mRNA for the myosin essential light chains and the corresponding proteins did not change significantly in either muscle type. No alterations in non-muscle myosin heavy chain isoforms could be detected after thyroxine treatment. In conclusion, thyroxine treatment alters the isoform composition of myosin in fast and slow smooth muscles in vivo. This change is sufficient to increase shortening velocity and sensitivity of isometric force to P(i) in the fast, but not in the slow, smooth muscle type. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physiology
volume
543
issue
3
pages
757 - 766
publisher
The Physiological Society
external identifiers
  • wos:000178374300004
  • pmid:12231636
  • scopus:0037106415
ISSN
1469-7793
DOI
10.1113/jphysiol.2002.025494
language
English
LU publication?
yes
id
65876d85-97f6-40aa-a96a-8d8451873629 (old id 110280)
date added to LUP
2007-06-26 11:10:42
date last changed
2017-02-05 04:25:31
@article{65876d85-97f6-40aa-a96a-8d8451873629,
  abstract     = {Information on the effects of thyroid hormone on smooth muscle contractile protein expression and mechanical properties is sparse. We have addressed the following questions. (1) Can thyroxine hormone alter myosin isoform composition in smooth muscle? (2) Can a change in myosin isoform composition lead to altered mechanical properties in smooth muscle? (3) Are alterations, if occurring, equal in fast and slow smooth muscle types? Guinea-pigs were treated with thyroxine (T(4)) for 12 days. Control animals were given physiological saline solution. Maximal unloaded shortening velocity (V(max)) was measured in chemically skinned, maximally activated muscle preparations from the aorta and the taenia coli. V(max) increased following thyroxine treatment, by approximately 20 % in the taenia coli. In the aorta, no significant increase in V(max) could be detected. The sensitivity of isometric force to inorganic phosphate (P(i)) was increased in the taenia coli following thyroxine treatment. The expression of mRNA (determined with RT-PCR) for the myosin heavy chain with the seven amino acid insert increased by approximately 70 % in the aorta and about 25 % in the taenia coli following thyroxine treatment. Western blot analysis showed an increase in the inserted myosin heavy chain form in the taenia coli. Expression of mRNA for the myosin essential light chains and the corresponding proteins did not change significantly in either muscle type. No alterations in non-muscle myosin heavy chain isoforms could be detected after thyroxine treatment. In conclusion, thyroxine treatment alters the isoform composition of myosin in fast and slow smooth muscles in vivo. This change is sufficient to increase shortening velocity and sensitivity of isometric force to P(i) in the fast, but not in the slow, smooth muscle type.},
  author       = {Löfgren, Mia and Fagher, Katarina and Woodard, Geoffrey and Arner, Anders},
  issn         = {1469-7793},
  language     = {eng},
  number       = {3},
  pages        = {757--766},
  publisher    = {The Physiological Society},
  series       = {Journal of Physiology},
  title        = {Effects of thyroxine on myosin isoform expression and mechanical properties in guinea-pig smooth muscle.},
  url          = {http://dx.doi.org/10.1113/jphysiol.2002.025494},
  volume       = {543},
  year         = {2002},
}