Logarithmic superposition of force response with rapid length changes in relaxed porcine airway smooth muscle

G. Ijpma, A. M. Al-Jumaily, S. P. Cairns, Gary C Sieck

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

We present a systematic quantitative analysis of power-law force relaxation and investigate logarithmic superposition of force response in relaxed porcine airway smooth muscle (ASM) strips in vitro. The term logarithmic superposition describes linear superposition on a logarithmic scale, which is equivalent to multiplication on a linear scale. Additionally, we examine whether the dynamic response of contracted and relaxed muscles is dominated by cross-bridge cycling or passive dynamics. The study shows the following main findings. For relaxed ASM, the force response to length steps of varying amplitude (0.25-4% of reference length, both lengthening and shortening) are well-fitted with powerlaw functions over several decades of time (10 -2 to 10 3 s), and the force response after consecutive length changes is more accurately fitted assuming logarithmic superposition rather than linear superposition. Furthermore, for sinusoidal length oscillations in contracted and relaxed muscles, increasing the oscillation amplitude induces greater hysteresivity and asymmetry of force-length relationships, whereas increasing the frequency dampens hysteresivity but increases asymmetry. We conclude that logarithmic superposition is an important feature of relaxed ASM, which may facilitate a more accurate prediction of force responses in the continuous dynamic environment of the respiratory system. In addition, the single power-function response to length changes shows that the dynamics of cross-bridge cycling can be ignored in relaxed muscle. The similarity in response between relaxed and contracted states implies that the investigated passive dynamics play an important role in both states and should be taken into account.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume299
Issue number6
DOIs
StatePublished - Dec 2010

Fingerprint

Smooth Muscle
Swine
Muscles
Respiratory System
In Vitro Techniques

Keywords

  • Power-law force relaxation
  • Smooth muscle dynamics

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology
  • Physiology

Cite this

Logarithmic superposition of force response with rapid length changes in relaxed porcine airway smooth muscle. / Ijpma, G.; Al-Jumaily, A. M.; Cairns, S. P.; Sieck, Gary C.

In: American Journal of Physiology - Lung Cellular and Molecular Physiology, Vol. 299, No. 6, 12.2010.

Research output: Contribution to journalArticle

@article{ae99248a9e864d7c9bb9fc9ec429bef6,
title = "Logarithmic superposition of force response with rapid length changes in relaxed porcine airway smooth muscle",
abstract = "We present a systematic quantitative analysis of power-law force relaxation and investigate logarithmic superposition of force response in relaxed porcine airway smooth muscle (ASM) strips in vitro. The term logarithmic superposition describes linear superposition on a logarithmic scale, which is equivalent to multiplication on a linear scale. Additionally, we examine whether the dynamic response of contracted and relaxed muscles is dominated by cross-bridge cycling or passive dynamics. The study shows the following main findings. For relaxed ASM, the force response to length steps of varying amplitude (0.25-4{\%} of reference length, both lengthening and shortening) are well-fitted with powerlaw functions over several decades of time (10 -2 to 10 3 s), and the force response after consecutive length changes is more accurately fitted assuming logarithmic superposition rather than linear superposition. Furthermore, for sinusoidal length oscillations in contracted and relaxed muscles, increasing the oscillation amplitude induces greater hysteresivity and asymmetry of force-length relationships, whereas increasing the frequency dampens hysteresivity but increases asymmetry. We conclude that logarithmic superposition is an important feature of relaxed ASM, which may facilitate a more accurate prediction of force responses in the continuous dynamic environment of the respiratory system. In addition, the single power-function response to length changes shows that the dynamics of cross-bridge cycling can be ignored in relaxed muscle. The similarity in response between relaxed and contracted states implies that the investigated passive dynamics play an important role in both states and should be taken into account.",
keywords = "Power-law force relaxation, Smooth muscle dynamics",
author = "G. Ijpma and Al-Jumaily, {A. M.} and Cairns, {S. P.} and Sieck, {Gary C}",
year = "2010",
month = "12",
doi = "10.1152/ajplung.00023.2010",
language = "English (US)",
volume = "299",
journal = "American Journal of Physiology - Renal Fluid and Electrolyte Physiology",
issn = "1931-857X",
publisher = "American Physiological Society",
number = "6",

}

TY - JOUR

T1 - Logarithmic superposition of force response with rapid length changes in relaxed porcine airway smooth muscle

AU - Ijpma, G.

AU - Al-Jumaily, A. M.

AU - Cairns, S. P.

AU - Sieck, Gary C

PY - 2010/12

Y1 - 2010/12

N2 - We present a systematic quantitative analysis of power-law force relaxation and investigate logarithmic superposition of force response in relaxed porcine airway smooth muscle (ASM) strips in vitro. The term logarithmic superposition describes linear superposition on a logarithmic scale, which is equivalent to multiplication on a linear scale. Additionally, we examine whether the dynamic response of contracted and relaxed muscles is dominated by cross-bridge cycling or passive dynamics. The study shows the following main findings. For relaxed ASM, the force response to length steps of varying amplitude (0.25-4% of reference length, both lengthening and shortening) are well-fitted with powerlaw functions over several decades of time (10 -2 to 10 3 s), and the force response after consecutive length changes is more accurately fitted assuming logarithmic superposition rather than linear superposition. Furthermore, for sinusoidal length oscillations in contracted and relaxed muscles, increasing the oscillation amplitude induces greater hysteresivity and asymmetry of force-length relationships, whereas increasing the frequency dampens hysteresivity but increases asymmetry. We conclude that logarithmic superposition is an important feature of relaxed ASM, which may facilitate a more accurate prediction of force responses in the continuous dynamic environment of the respiratory system. In addition, the single power-function response to length changes shows that the dynamics of cross-bridge cycling can be ignored in relaxed muscle. The similarity in response between relaxed and contracted states implies that the investigated passive dynamics play an important role in both states and should be taken into account.

AB - We present a systematic quantitative analysis of power-law force relaxation and investigate logarithmic superposition of force response in relaxed porcine airway smooth muscle (ASM) strips in vitro. The term logarithmic superposition describes linear superposition on a logarithmic scale, which is equivalent to multiplication on a linear scale. Additionally, we examine whether the dynamic response of contracted and relaxed muscles is dominated by cross-bridge cycling or passive dynamics. The study shows the following main findings. For relaxed ASM, the force response to length steps of varying amplitude (0.25-4% of reference length, both lengthening and shortening) are well-fitted with powerlaw functions over several decades of time (10 -2 to 10 3 s), and the force response after consecutive length changes is more accurately fitted assuming logarithmic superposition rather than linear superposition. Furthermore, for sinusoidal length oscillations in contracted and relaxed muscles, increasing the oscillation amplitude induces greater hysteresivity and asymmetry of force-length relationships, whereas increasing the frequency dampens hysteresivity but increases asymmetry. We conclude that logarithmic superposition is an important feature of relaxed ASM, which may facilitate a more accurate prediction of force responses in the continuous dynamic environment of the respiratory system. In addition, the single power-function response to length changes shows that the dynamics of cross-bridge cycling can be ignored in relaxed muscle. The similarity in response between relaxed and contracted states implies that the investigated passive dynamics play an important role in both states and should be taken into account.

KW - Power-law force relaxation

KW - Smooth muscle dynamics

UR - http://www.scopus.com/inward/record.url?scp=78649815105&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=78649815105&partnerID=8YFLogxK

U2 - 10.1152/ajplung.00023.2010

DO - 10.1152/ajplung.00023.2010

M3 - Article

C2 - 20817779

AN - SCOPUS:78649815105

VL - 299

JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

SN - 1931-857X

IS - 6

ER -