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Isoform distribution and tissue contents of contractile and cytoskeletal proteins in hypertrophied smooth muscle from rat portal vein

Malmqvist, Ulf LU and Arner, Anders LU (1990) In Circulation Research 66(3). p.832-845
Abstract
Growth of the smooth muscle in the rat portal vein was initiated by an increased transmural pressure. After 7 days, the cross-sectional area of the vessel wall and the maximal active force of the longitudinal muscle layer had increased twofold. Electron microscopy showed that the cell cross-sectional area was increased, suggesting cellular hypertrophy. Increased amounts of intermediate (10 nm) filaments were observed in the hypertrophied cells. The hypertrophied vessels had decreased DNA content per unit wet weight compared with the control vessels (hypertrophied, 1.5 +/- 0.1; control, 1.9 +/- 0.1 micrograms/mg; p less than 0.01). Protein composition was studied with electrophoretic methods. Compared with control preparations the... (More)
Growth of the smooth muscle in the rat portal vein was initiated by an increased transmural pressure. After 7 days, the cross-sectional area of the vessel wall and the maximal active force of the longitudinal muscle layer had increased twofold. Electron microscopy showed that the cell cross-sectional area was increased, suggesting cellular hypertrophy. Increased amounts of intermediate (10 nm) filaments were observed in the hypertrophied cells. The hypertrophied vessels had decreased DNA content per unit wet weight compared with the control vessels (hypertrophied, 1.5 +/- 0.1; control, 1.9 +/- 0.1 micrograms/mg; p less than 0.01). Protein composition was studied with electrophoretic methods. Compared with control preparations the hypertrophied veins had similar myosin and actin contents per unit wet weight (myosin: hypertrophied, 4.4 +/- 0.8; control, 5.9 +/- 0.9; actin: hypertrophied 12.2 +/- 0.6; control, 11.8 +/- 1.0 mg/g). Two different forms of the myosin heavy chain were detected with 5% sodium dodecyl sulfate-polyacrylamide gels. The proportion of the lower molecular weight heavy chain relative to total heavy chain content was about 30% and similar in both preparations. The relation filamin/myosin was increased in the hypertrophied vessels. Pyrophosphate gel electrophoresis revealed two protein bands, with an increase in the slower migrating band in the hypertrophied vessels possibly reflecting an increase in filamin content in the extracts. In the control portal vein alpha-actin is the dominating isoform constituting about 55% of total actin. In hypertrophied vessels, alpha-actin decreased (by 15%) and gamma-actin increased (by 20%). The portal vein contained desmin and vimentin in a ratio of about 6:1. The hypertrophied vessels showed a marked increase in the amount of these proteins (desmin/actin: hypertrophied, 0.32; control, 0.14). In conclusion, during pressure-induced growth of the portal vein, contractile protein contents increase in proportion to the increase in weight. A change in isoforms of actin occurs but no evidence for a change in myosin isoforms was found. The structural proteins increase relative to tissue weight, possibly associated with the increased number of intermediate filaments demonstrated with electron microscopy. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Circulation Research
volume
66
issue
3
pages
832 - 845
publisher
American Heart Association
external identifiers
  • pmid:2306809
  • scopus:0025250070
ISSN
0009-7330
language
English
LU publication?
yes
id
502b62b7-77d8-4f16-a64a-3685e205cbe5 (old id 1105468)
alternative location
http://circres.ahajournals.org/cgi/reprint/66/3/832
date added to LUP
2008-08-05 15:54:13
date last changed
2017-08-27 05:39:30
@article{502b62b7-77d8-4f16-a64a-3685e205cbe5,
  abstract     = {Growth of the smooth muscle in the rat portal vein was initiated by an increased transmural pressure. After 7 days, the cross-sectional area of the vessel wall and the maximal active force of the longitudinal muscle layer had increased twofold. Electron microscopy showed that the cell cross-sectional area was increased, suggesting cellular hypertrophy. Increased amounts of intermediate (10 nm) filaments were observed in the hypertrophied cells. The hypertrophied vessels had decreased DNA content per unit wet weight compared with the control vessels (hypertrophied, 1.5 +/- 0.1; control, 1.9 +/- 0.1 micrograms/mg; p less than 0.01). Protein composition was studied with electrophoretic methods. Compared with control preparations the hypertrophied veins had similar myosin and actin contents per unit wet weight (myosin: hypertrophied, 4.4 +/- 0.8; control, 5.9 +/- 0.9; actin: hypertrophied 12.2 +/- 0.6; control, 11.8 +/- 1.0 mg/g). Two different forms of the myosin heavy chain were detected with 5% sodium dodecyl sulfate-polyacrylamide gels. The proportion of the lower molecular weight heavy chain relative to total heavy chain content was about 30% and similar in both preparations. The relation filamin/myosin was increased in the hypertrophied vessels. Pyrophosphate gel electrophoresis revealed two protein bands, with an increase in the slower migrating band in the hypertrophied vessels possibly reflecting an increase in filamin content in the extracts. In the control portal vein alpha-actin is the dominating isoform constituting about 55% of total actin. In hypertrophied vessels, alpha-actin decreased (by 15%) and gamma-actin increased (by 20%). The portal vein contained desmin and vimentin in a ratio of about 6:1. The hypertrophied vessels showed a marked increase in the amount of these proteins (desmin/actin: hypertrophied, 0.32; control, 0.14). In conclusion, during pressure-induced growth of the portal vein, contractile protein contents increase in proportion to the increase in weight. A change in isoforms of actin occurs but no evidence for a change in myosin isoforms was found. The structural proteins increase relative to tissue weight, possibly associated with the increased number of intermediate filaments demonstrated with electron microscopy.},
  author       = {Malmqvist, Ulf and Arner, Anders},
  issn         = {0009-7330},
  language     = {eng},
  number       = {3},
  pages        = {832--845},
  publisher    = {American Heart Association},
  series       = {Circulation Research},
  title        = {Isoform distribution and tissue contents of contractile and cytoskeletal proteins in hypertrophied smooth muscle from rat portal vein},
  volume       = {66},
  year         = {1990},
}