Contraction history modulates isotonic shortening velocity in smooth muscle

S. J. Gunst, M. F. Wu, D. D. Smith

Research output: Contribution to journalArticle

46 Scopus citations

Abstract

The effect of contraction history on the isotonic shortening velocity of canine tracheal smooth muscle was investigated. Muscles were contracted isometrically for 20 s at initial lengths of L(o) (length of maximal active force), 85% L(o), or 70% L(o) using electrical field stimulation. Muscles were then allowed to shorten isotonically under different afterloads either with or without first being subjected to a step decrease in length to 70% L(o). Instantaneous velocities were plotted against instantaneous muscle length during isotonic shortening. Regardless of protocol, the velocity at any muscle length during shortening was lower when the muscle was initially activated at a longer length. The isotonic shortening velocity decreased progressively during shortening at a nearly linear rate with respect to instantaneous muscle length under all conditions. Results suggest that a longer muscle length at the time of activation leads to the development of higher loads on the contractile element during subsequent shortening, resulting in a slower shortening velocity. This plasticity of the force- velocity relationship may result from cytostructural reorganization of the smooth muscle cells in response to contractile activation at different muscle lengths.

Original languageEnglish (US)
Pages (from-to)C467-C476
JournalAmerican Journal of Physiology - Cell Physiology
Volume265
Issue number2 34-2
DOIs
StatePublished - Jan 1 1993

Keywords

  • cytoskeleton
  • force-velocity curve
  • shortening deactivation
  • smooth muscle hysteresis
  • smooth muscle plasticity
  • tracheal smooth muscle

ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Physiology

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