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Does smooth muscle in an intact airway undergo length adaptation during a sustained change in transmural pressure?

Ansell, T.K., McFawn, P.K., McLaughlin, R.A., Sampson, David, Eastwood, P.R., Hillman, D.R., Mitchell, H.W. and Noble, P.B. (2015) Does smooth muscle in an intact airway undergo length adaptation during a sustained change in transmural pressure? Journal of Applied Physiology, 118 (5). pp. 533-543.

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In isolated airway smooth muscle (ASM) strips, an increase or decrease in ASM length away from its current optimum length causes an immediate reduction in force production followed by a gradual time-dependent recovery in force, a phenomenon termed length adaptation. In situ, length adaptation may be initiated by a change in transmural pressure (Ptm), which is a primary physiological determinant of ASM length. The present study sought to determine the effect of sustained changes in Ptm and therefore, ASM perimeter, on airway function. We measured contractile responses in whole porcine bronchial segments in vitro before and after a sustained inflation from a baseline Ptm of 5 cmH2O to 25 cmH2O, or deflation to −5 cmH2O, for ∼50 min in each case. In one group of airways, lumen narrowing and stiffening in response to electrical field stimulation (EFS) were assessed from volume and pressure signals using a servo-controlled syringe pump with pressure feedback. In a second group of airways, lumen narrowing and the perimeter of the ASM in situ were determined by anatomical optical coherence tomography. In a third group of airways, active tension was determined under isovolumic conditions. Both inflation and deflation reduced the contractile response to EFS. Sustained Ptm change resulted in a further decrease in contractile response, which returned to baseline levels upon return to the baseline Ptm. These findings reaffirm the importance of Ptm in regulating airway narrowing. However, they do not support a role for ASM length adaptation in situ under physiological levels of ASM lengthening and shortening.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences
Faculty of Health and Medical Sciences
Authors :
Ansell, T.K.
McFawn, P.K.
McLaughlin, R.A.
Eastwood, P.R.
Hillman, D.R.
Mitchell, H.W.
Noble, P.B.
Date : 2015
DOI : 10.1152/japplphysiol.00724.2014
Uncontrolled Keywords : Airway smooth muscle, Anatomical optical coherence tomography (aOCT), Bronchoconstriction, Length adaptation, adaptation, animal, bronchoconstriction, bronchus, electrostimulation, male, muscle contraction, pathophysiology, physiology, pig, pressure, procedures, respiratory system, smooth muscle, Adaptation, Physiological, Animals, Bronchi, Bronchoconstriction, Electric Stimulation, Male, Muscle Contraction, Muscle, Smooth, Pressure, Respiratory System, Swine
Depositing User : Maria Rodriguez-Marquez
Date Deposited : 04 Jun 2018 09:59
Last Modified : 19 Sep 2018 11:32

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