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Repeated Measurement of Respiratory Muscle Activity and Ventilation in Mouse Models of Neuromuscular Disease
Published on: April 17, 2017
Respiratory muscle fiber remodeling in chronic hyperinflation: dysfunction or adaptation?
Thomas L Clanton1, Sanford Levine
1Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida 32611, USA. tclanton@hhp.ufl.edu
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 11, 2009
Summary
Respiratory muscles in chronic obstructive pulmonary disease (COPD) adapt differently in humans versus animals. Human diaphragm adaptations, including fiber shifts and atrophy, are likely adaptive responses to altered breathing mechanics, not dysfunction.
Area of Science:
- Respiratory Physiology
- Muscle Biology
- Pulmonary Disease Research
Background:
- Diaphragm and respiratory muscles remodel in emphysema and chronic obstructive pulmonary disease (COPD).
- Adaptations differ between animal models and human COPD.
- Common features include improved endurance and increased oxidative capacity.
Purpose of the Study:
- To compare diaphragm remodeling in human COPD and animal models of emphysema.
- To challenge the notion that human diaphragm adaptations represent dysfunction.
- To propose that observed changes are adaptive responses to altered respiratory mechanics.
Main Methods:
- Review of existing literature comparing human COPD and rodent emphysema models.
- Analysis of diaphragm muscle fiber type shifts, myosin isoforms, and atrophy.
- Examination of specific force, oxidative capacity, and Ca(2+) sensitivity.
Main Results:
- Human diaphragms show shifts to Type I fibers, Type I/II atrophy, and increased oxidative capacity.
- Rodent models lack consistent specific force loss or fiber population shifts; atrophy mainly in Type IIX fibers.
- Human diaphragm adaptations may involve reduced Ca(2+) sensitivity and myofibrillar elastic recoil.
Conclusions:
- Human diaphragm adaptations in COPD are distinct from rodent models.
- Observed changes in human diaphragms are likely adaptive, not solely indicative of dysfunction.
- These adaptations reflect a complex muscle responding to a unique working environment.
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