F-actin stabilization increases tension cost during contraction of permeabilized airway smooth muscle in dogs

Keith A. Jones, William J. Perkins, Robert R. Lorenz, Y.s. Prakash, Gary C Sieck, David Oman Warner

Research output: Contribution to journalArticle

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Abstract

1. Dynamic actin reorganization involving actin polymerization and depolymerization may play an important functional role in smooth muscle. 2. This study tested the hypothesis that F-actin stabilization by phalloidin increases tension cost (i.e. ATP hydrolysis rate per unit of isometric force) during Ca2+-induced activation of Triton X-100-permeabilized canine tracheal smooth muscle. 3. Adenosine 5'-triphosphate (ATP) hydrolysis rate was quantified using an enzyme-coupled NADH fluorometric technique, regulatory myosin light chain (rMLC) phosphorylation was measured by Western blot analysis, and maximum unloaded shortening velocity (V(max)) was estimated by interpolation of the force-velocity relationship to zero load during isotonic loading. 4. Maximal activation with 10 μM free Ca2+ induced sustained increases in isometric force, stiffness, and rMLC phosphorylation. However, the increase in ATP hydrolysis rate initially reached peak values, but then declined to steady-state levels above that of the unstimulated muscle. Thus, tension cost decreased throughout steady-state isometric force. 5. Following incubation of permeabilized strips with 50 μM phalloidin for 1 h, the increases in isometric force and stiffness were not sustained despite a sustained increase in rMLC phosphorylation. Also, after an initial decline, tension cost increased throughout activation. Phalloidin had no effect on V(max) during steady-state isometric force or on rMLC phosphorylation. 6. These findings suggest that dynamic reorganization of actin is necessary for optimal energy utilization during contraction of permeabilized airway smooth muscle.

Original languageEnglish (US)
Pages (from-to)527-538
Number of pages12
JournalJournal of Physiology
Volume519
Issue number2
DOIs
StatePublished - Sep 1 1999

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Myosin Light Chains
Phalloidine
Smooth Muscle
Actins
Phosphorylation
Dogs
Costs and Cost Analysis
Hydrolysis
Adenosine Triphosphate
Octoxynol
Polymerization
NAD
Canidae
Western Blotting
Muscles
Enzymes

ASJC Scopus subject areas

  • Physiology

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F-actin stabilization increases tension cost during contraction of permeabilized airway smooth muscle in dogs. / Jones, Keith A.; Perkins, William J.; Lorenz, Robert R.; Prakash, Y.s.; Sieck, Gary C; Warner, David Oman.

In: Journal of Physiology, Vol. 519, No. 2, 01.09.1999, p. 527-538.

Research output: Contribution to journalArticle

Jones, Keith A. ; Perkins, William J. ; Lorenz, Robert R. ; Prakash, Y.s. ; Sieck, Gary C ; Warner, David Oman. / F-actin stabilization increases tension cost during contraction of permeabilized airway smooth muscle in dogs. In: Journal of Physiology. 1999 ; Vol. 519, No. 2. pp. 527-538.
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