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Updated: Aug 17, 2026
In vitro Measurements of Tracheal Constriction Using Mice
Published on: June 25, 2012
Maturation of guinea pig tracheal strip stiffness
Lu Wang1, Pasquale Chitano, Thomas M Murphy
1Dept. of Pediatrics, Duke University Medical Center, Rm. 302, Bell Bldg., Box 2994, Durham, NC 27710, USA. lu.wang@duke.edu
Insights
Juvenile guinea pigs have less stiff tracheal tissue, contributing to reduced airway smooth muscle resistance and faster shortening velocity compared to infants and adults.
Area of Science:
- Physiology
- Biomechanical Engineering
- Developmental Biology
Background:
- Previous studies demonstrated age-related differences in guinea pig tracheal strip shortening velocity.
- The greatest shortening velocity was linked to the least resistance to shortening in juvenile animals.
Purpose of the Study:
- To investigate age-related differences in tracheal tissue stiffness.
- To determine if lower stiffness in juvenile tracheal strips explains their reduced resistance and increased shortening velocity.
Main Methods:
- Static stiffness was measured using stepwise deformations.
- Dynamic stiffness and phase angle were evaluated using oscillatory deformations in unstimulated and stimulated tracheal strips.
- Measurements were compared across infant, juvenile, and adult guinea pigs.
Main Results:
- Static stiffness showed no significant age-related differences.
- Unstimulated juvenile tracheal strips exhibited significantly lower dynamic stiffness and phase angle compared to infant and adult groups.
- These differences in dynamic stiffness were abolished during muscle contraction.
Conclusions:
- Tracheal tissue in juvenile guinea pigs is less stiff and contains fewer viscous elements than in infants and adults.
- This reduced stiffness in non-contractile components may functionally explain the lower resistance and higher shortening velocity observed in juvenile airway smooth muscle.
- These findings highlight developmental changes in airway biomechanics.
Abstract:
Previously, we showed the shortening velocity of guinea pig tracheal strips was the greatest in juvenile (3-wk-old) compared with infant (1-wk-old) and adult animals (3-mo-old). The greatest shortening velocity was associated with the least resistance to shortening calculated from force-velocity curves among the three age groups. It remained to be verified if the stiffness of tracheal tissue, a measure of tissue response to geometrical deformations, is different among the three age groups. We hypothesized that stiffness of intact tracheal strips is lowest in the juvenile group and that this can explain the ontogeny of airway smooth muscle resistance to shortening and shortening velocity. Static stiffness measured through stepwise deformations showed no age-related differences. Evaluation of tissue response to oscillatory deformations showed that the dynamic stiffness of unstimulated tracheal strips was 8.35 +/- 0.88, 4.15 +/- 1.09, and 8.21 +/- 1.57 kPa, and the phase angle was 10.3 +/- 2.93, 2.46 +/- 0.67, and 7.87 +/- 1.77 degrees in infant, juvenile, and adult, respectively. Unstimulated juvenile strips were significantly lower in dynamic stiffness and phase angle compared with unstimulated infant or adult strips. This maturational profile was independent of muscle strip preset length or oscillation mode/amplitude but was abolished at peak of contraction to either carbachol or electric field stimulation. These results suggest that the noncontractile components of tracheal strips are less stiff and contain fewer viscous/frictional elements in juvenile than in other age groups. This may provide a functional basis for reduced resistance to length changes in juvenile airway smooth muscle.
