Document Type

Article

Original Publication Date

2017

Journal/Book/Conference Title

AMERICAN JOURNAL OF PHYSIOLOGY-RENAL PHYSIOLOGY

Volume

313

Issue

1

First Page

F126

Last Page

F134

DOI of Original Publication

10.1152/ajprenal.00633.2016

Comments

Originally published at http://doi.org/10.1152/ajprenal.00633.2016

Date of Submission

August 2017

Abstract

Biological soft tissues are viscoelastic because they display timeindependent pseudoelasticity and time-dependent viscosity. However, there is evidence that the bladder may also display plasticity, defined as an increase in strain that is unrecoverable unless work is done by the muscle. In the present study, an electronic lever was used to induce controlled changes in stress and strain to determine whether rabbit detrusor smooth muscle (rDSM) is best described as viscoelastic or viscoelastic plastic. Using sequential ramp loading and unloading cycles, stress-strain and stiffness-stress analyses revealed that rDSM displayed reversible viscoelasticity, and that the viscous component was responsible for establishing a high stiffness at low stresses that increased only modestly with increasing stress compared with the large increase produced when the viscosity was absent and only pseudoelasticity governed tissue behavior. The study also revealed that rDSM underwent softening correlating with plastic deformation and creep that was reversed slowly when tissues were incubated in a Ca2+ -containing solution. Together, the data support a model of DSM as a viscoelastic-plastic material, with the plasticity resulting from motor protein activation. This model explains the mechanism of intrinsic bladder compliance as "slipping" cross bridges, predicts that wall tension is dependent not only on vesicle pressure and radius but also on actomyosin cross-bridge activity, and identifies a novel molecular target for compliance regulation, both physiologically and therapeutically.

Rights

Copyright © 2017 the American Physiological Society

Is Part Of

VCU Biochemistry and Molecular Biology Publications

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