Advanced

Effects of Ca2+ on force-velocity characteristics of normal and hypertrophic smooth muscle of the rat portal vein

Arner, Anders LU ; Malmqvist, Ulf LU and Uvelius, Bengt LU (1985) In Acta Physiologica Scandinavica 124(4). p.525-533
Abstract
Portal hypertension was induced in rats by partial ligation of the hepatic branches of the portal vein. After 5 days of hypertension the portal veins were taken out and mounted for isometric and quick-release experiments. Portal veins from sham-operated normal rats served as controls. The ligated veins had an increased cross-sectional area, indicating smooth-muscle hypertrophy. Although the absolute magnitude of active force of these veins was increased, the active force per cross-sectional area was decreased, indicating an alteration in the properties of the contractile system. No difference in the Ca2+ concentration-response relations to K+-activated intact control and hypertrophic veins was found. In chemically skinned preparations,... (More)
Portal hypertension was induced in rats by partial ligation of the hepatic branches of the portal vein. After 5 days of hypertension the portal veins were taken out and mounted for isometric and quick-release experiments. Portal veins from sham-operated normal rats served as controls. The ligated veins had an increased cross-sectional area, indicating smooth-muscle hypertrophy. Although the absolute magnitude of active force of these veins was increased, the active force per cross-sectional area was decreased, indicating an alteration in the properties of the contractile system. No difference in the Ca2+ concentration-response relations to K+-activated intact control and hypertrophic veins was found. In chemically skinned preparations, devoid of functional plasma membranes, the hypertrophic veins had similar Ca2+ sensitivity (in the presence of I microM calmodulin) but a lower force per cross-sectional area. Force-velocity relations were determined in K+-activated intact preparations. In control veins a reduction in extracellular Ca2+ was associated with a significant reduction in both isometric force and maximal shortening velocity (Vmax). In hypertrophic veins the decreased isometric force at maximal activation was associated with a low Vmax. A comparison between hypertrophic and submaximally stimulated control vessels showed corresponding Vmax and isometric force values. We conclude that the low isometric force of hypertrophic veins is associated with a lower rate of cross-bridge turnover. This could be an effect of alterations in the activation mechanisms or in the intrinsic properties of the contractile system itself. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Acta Physiologica Scandinavica
volume
124
issue
4
pages
525 - 533
publisher
Wiley-Blackwell
external identifiers
  • pmid:4050479
  • scopus:0022271366
ISSN
0001-6772
language
English
LU publication?
yes
id
b50ae017-90e8-4303-a78b-c7a2e71798db (old id 1103458)
date added to LUP
2008-08-11 14:18:42
date last changed
2017-02-22 11:44:30
@article{b50ae017-90e8-4303-a78b-c7a2e71798db,
  abstract     = {Portal hypertension was induced in rats by partial ligation of the hepatic branches of the portal vein. After 5 days of hypertension the portal veins were taken out and mounted for isometric and quick-release experiments. Portal veins from sham-operated normal rats served as controls. The ligated veins had an increased cross-sectional area, indicating smooth-muscle hypertrophy. Although the absolute magnitude of active force of these veins was increased, the active force per cross-sectional area was decreased, indicating an alteration in the properties of the contractile system. No difference in the Ca2+ concentration-response relations to K+-activated intact control and hypertrophic veins was found. In chemically skinned preparations, devoid of functional plasma membranes, the hypertrophic veins had similar Ca2+ sensitivity (in the presence of I microM calmodulin) but a lower force per cross-sectional area. Force-velocity relations were determined in K+-activated intact preparations. In control veins a reduction in extracellular Ca2+ was associated with a significant reduction in both isometric force and maximal shortening velocity (Vmax). In hypertrophic veins the decreased isometric force at maximal activation was associated with a low Vmax. A comparison between hypertrophic and submaximally stimulated control vessels showed corresponding Vmax and isometric force values. We conclude that the low isometric force of hypertrophic veins is associated with a lower rate of cross-bridge turnover. This could be an effect of alterations in the activation mechanisms or in the intrinsic properties of the contractile system itself.},
  author       = {Arner, Anders and Malmqvist, Ulf and Uvelius, Bengt},
  issn         = {0001-6772},
  language     = {eng},
  number       = {4},
  pages        = {525--533},
  publisher    = {Wiley-Blackwell},
  series       = {Acta Physiologica Scandinavica},
  title        = {Effects of Ca2+ on force-velocity characteristics of normal and hypertrophic smooth muscle of the rat portal vein},
  volume       = {124},
  year         = {1985},
}