Transition from phasic to tonic contractility in airway smooth muscle after birth: An experimental and computational modeling study

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Abstract

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.
Original languageEnglish
Pages (from-to)011003-1 - 011003-9
Number of pages9
JournalASME Journal of Engineering and Science in Medical Diagnostics and Therapy
Volume2
Issue number1
DOIs
Publication statusPublished - 8 Feb 2019

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Smooth Muscle
Parturition
Muscle Contraction
Sheep
Pregnancy
Muscle Development
Cell Count
Phenotype

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title = "Transition from phasic to tonic contractility in airway smooth muscle after birth: An experimental and computational modeling study",
abstract = "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.",
author = "Kimberley Wang and Amy Chang and Jennifer Pillow and Bela Suki and Peter Noble",
year = "2019",
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T1 - Transition from phasic to tonic contractility in airway smooth muscle after birth

T2 - An experimental and computational modeling study

AU - Wang, Kimberley

AU - Chang, Amy

AU - Pillow, Jennifer

AU - Suki, Bela

AU - Noble, Peter

PY - 2019/2/8

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N2 - 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.

AB - 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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