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Human lung parenchyma responds to contractile stimulation
M Dolhnikoff1, J Morin, M S Ludwig
1Meakins-Christie Laboratories, Department of Medicine, Royal Victoria Hospital, Department of Surgery, Royal Victoria Hospital, McGill University, Montreal, Canada.
American Journal of Respiratory and Critical Care Medicine
|November 17, 1998
Summary
Human lung tissue shows increased resistance after acetylcholine challenge. This response occurs even without small airways, suggesting direct contraction in alveolar walls.
Area of Science:
- Pulmonary physiology
- Respiratory mechanics
- Cellular contractility
Background:
- Airway smooth muscle contraction increases lung tissue resistance.
- The role of parenchymal cells in dynamic lung mechanics is not fully understood.
Purpose of the Study:
- To investigate the viscoelastic properties of human lung parenchymal strips after acetylcholine challenge.
- To determine if small airways are necessary for the parenchymal response to acetylcholine.
Main Methods:
- Human subpleural parenchymal strips were oscillated in an organ bath to measure resistance, elastance, and hysteresivity.
- Tissues underwent morphometric and immunohistochemical analysis to quantify cellular components, including smooth muscle actin.
- Acetylcholine (ACh) was used to challenge the tissue strips.
Main Results:
- Acetylcholine challenge significantly increased tension, resistance, elastance, and hysteresivity in lung parenchymal strips.
- The mechanical response to ACh was similar in strips with and without identifiable airways.
- Smooth muscle actin content in alveolar walls did not differ between groups.
Conclusions:
- Human lung parenchymal strips exhibit altered dynamic mechanical behavior in response to acetylcholine.
- The contractile response to acetylcholine in lung parenchyma does not require the presence of small airways.
- These findings suggest a direct contractile role for alveolar walls and/or alveolar ducts in lung mechanics.