Transition From Phasic to Tonic Contractility in Airway Smooth Muscle After Birth: An Experimental and Computational Modeling Study.

Authors:
Amy Y Chang
Amy Y Chang
Center for Cellular Construction
Bela Suki
Bela Suki
Boston University
United States
Peter B Noble
Peter B Noble
University of Western Australia
Australia

J Eng Sci Med Diagn Ther 2019 Feb 8;2(1). Epub 2019 Feb 8.

School of Human Sciences, The University of Western Australia, Crawley 6009, Western Australia, Australia.

Fetal airway smooth muscle (ASM) exhibits phasic contractile behavior, which transitions to a more sustained "tonic" contraction after birth. The timing and underlying mechanisms of ASM transition from a phasic to a tonic contractile phenotype are yet to be established. We characterized phasic ASM contraction in preterm (128 day gestation), term (~150 day gestation), 1-4 month, 1 yr, and adult sheep (5yr). Spontaneous phasic activity was measured in bronchial segments as amplitude, frequency, and intensity. The mechanism of phasic ASM contraction was investigated further with a computational model of ASM force development and lumen narrowing. The computational model comprised a two-dimensional cylindrical geometry of a network of contractile units and the activation of neighboring cells was dependent on the strength of coupling between cells. As expected, phasic contractions were most prominent in fetal airways and decreased with advancing age, to a level similar to the level in the 1-4 month lambs. Computational predictions demonstrated phasic contraction through the generation of a wave of activation events, the magnitude of which is determined by the number of active cells and the strength of cell-cell interactions. Decreases in phasic contraction with advancing age were simulated by reducing cell-cell coupling. Results show that phasic activity is suppressed rapidly after birth, then sustained at a lower intensity from the preweaning phase until adulthood in an ovine developmental model. Cell-cell coupling is proposed as a key determinant of phasic ASM contraction and if reduced could explain the observed maturational changes.

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Source
http://dx.doi.org/10.1115/1.4042312DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6467295PMC
February 2019

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Control of Human Airway Smooth Muscle: In Vitro Studies
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