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Airway smooth muscle and bronchospasm: fluctuating, fluidizing, freezing
Ramaswamy Krishnan1, Xavier Trepat, Trang T B Nguyen
1Program in Molecular and Integrative Physiological Sciences, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, United States.
Respiratory Physiology & Neurobiology
|June 3, 2008
Summary
Airways smooth muscle (ASM) behaves like a dynamic "glassy" material, explaining bronchospasm and why deep breaths fail to open airways in asthma. This finding reveals new insights into airway hyper-responsiveness.
Area of Science:
- Biophysics
- Cellular Biology
- Condensed Matter Physics
Background:
- Airways smooth muscle (ASM) plays a critical role in bronchospasm.
- Current understanding of ASM mechanics in asthma is incomplete.
- ASM remodeling and its dynamic responses are key factors in airway hyper-responsiveness.
Purpose of the Study:
- To review recent findings that fundamentally alter the understanding of ASM.
- To explore the intersection of condensed matter physics and ASM cytoskeletal biology.
- To elucidate the mechanical role of ASM in bronchospasm and airway hyper-responsiveness.
Main Methods:
- Review of four recent findings on ASM.
- Analysis of ASM remodeling processes.
- Comparison of ASM dynamics to soft glassy materials.
Main Results:
- ASM length is dynamically, not statically, equilibrated.
- ASM dynamics exhibit characteristics of soft glassy materials.
- Static force-length relationships do not describe dynamically contracted ASM.
- ASM cytoskeleton is fluidized by stretch.
Conclusions:
- ASM exhibits glassy dynamics, offering a new perspective on its mechanical behavior.
- These dynamics may explain the bronchodilatory effect of deep inspiration and its failure in asthma.
- Enhanced ASM mass in airway hyper-responsiveness is linked to these dynamic processes.
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