Mechanisms for the mechanical plasticity of tracheal smooth muscle

S. J. Gunst, R. A. Meiss, M. F. Wu, M. Rowe

Research output: Contribution to journalArticle

205 Scopus citations

Abstract

In smooth muscle tissues, the relationship between muscle or cell length and active force can be modulated by altering the cell or tissue length during stimulation. Mechanisms for this mechanical plasticity were investigated by measuring muscle stiffness during isometric contractions in which contractile force was graded by changing stimulus intensity or muscle length. Stiffness was significantly higher in contracted than in resting muscles at comparable forces; however, the relationship between stiffness and force during force development was curvilinear and independent of muscle length and stimulus intensity. This suggests that muscle stiffness during force development reflects properties of cellular components other than cross bridges which contribute to the series elasticity only during activation. During the tonic phase of isometric contraction, muscle stiffness increased while force remained constant. A step decrease in the length of a contracted muscle resulted in a high level of stiffness relative to force during isometric force redevelopment following the length step. We propose that the arrangement of the cytoskeleton can adjust to changes in the conformation of resting smooth muscle cells but that the organization of the cytoskeleton becomes more fixed upon contractile activation and is modulated very slowly during a sustained contraction. This may provide a mechanism for optimizing force development to the physical conformation of the cell at the time of activation.

Original languageEnglish (US)
Pages (from-to)C1267-C1276
JournalAmerican Journal of Physiology - Cell Physiology
Volume268
Issue number5 37-5
DOIs
StatePublished - 1995

Keywords

  • cross bridges
  • cytoskeleton
  • latch bridges
  • length-tension curve
  • shortening deactivation

ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Physiology
  • Agricultural and Biological Sciences(all)

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