HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 101/4/1189    most recent 00396.2006v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Speich, J. E. Articles by Ratz, P. H. Search for Related Content PubMed PubMed Citation Articles by Speich, J. E. Articles by Ratz, P. H.

A mechanical model for adjustable passive stiffness in rabbit detrusor

Departments of ¹Mechanical Engineering, ²Biomedical Engineering, ³Surgery, and ⁴Biochemistry and Pediatrics, Virginia Commonwealth University, Richmond, Virginia

Submitted 4 April 2006 ; accepted in final form 7 June 2006

Strips of rabbit detrusor smooth muscle (DSM) exhibit adjustable passive stiffness characterized by strain softening: a loss of stiffness on stretch to a new length distinct from viscoelastic behavior. At the molecular level, strain softening appears to be caused by cross-link breakage and is essentially irreversible when DSM is maintained under passive conditions (i.e., when cross bridges are not cycling to produce active force). However, on DSM activation, strain softening is reversible and likely due to cross-link reformation. Thus DSM displays adjustable passive stiffness that is dependent on the history of both muscle strain and activation. The present study provides empirical data showing that, in DSM, 1) passive isometric force relaxation includes a very slow component requiring hours to approach steady state, 2) the level of passive force maintained at steady state is less if the tissue has previously been strain softened, and 3) tissues subjected to a quick-release protocol exhibit a biphasic response consisting of passive force redevelopment followed by force relaxation. To explain these and previously identified characteristics, a mechanical model for adjustable passive stiffness is proposed based on the addition of a novel cross-linking element to a hybrid Kelvin/Voigt viscoelastic model.

smooth muscle mechanics; preconditioning; strain softening; passive force; muscle model

This article has been cited by other articles:

				A. L. Dorfmann, W. A Woods Jr, and B. A Trimmer Muscle performance in a soft-bodied terrestrial crawler: constitutive modelling of strain-rate dependency J R Soc Interface, March 6, 2008; 5(20): 349 - 362. [Abstract] [Full Text] [PDF]

				J. E. Speich, C. Dosier, L. Borgsmiller, K. Quintero, H. P. Koo, and P. H. Ratz Adjustable passive length-tension curve in rabbit detrusor smooth muscle J Appl Physiol, May 1, 2007; 102(5): 1746 - 1755. [Abstract] [Full Text] [PDF]