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Interactive effects of denervation and malnutrition on diaphragm structure and function
M I Lewis1, T J Lorusso, W Z Zhan
1Department of Medicine, Cedars-Sinai Medical Center Burns and Allen Research Institute, Cedars-Sinai Medical Center, University of California, Los Angeles School of Medicine 90048, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 1, 1996
Summary
Unilateral denervation and malnutrition significantly reduce diaphragm muscle force. This combined effect, unlike malnutrition alone, impairs muscle structure and function, leading to reduced force-generating capacity.
Area of Science:
- Physiology
- Muscle Biology
- Respiratory Medicine
Background:
- Diaphragm muscle (Dia) function is crucial for respiration.
- Understanding the impact of denervation (DN) and malnutrition (MN) on the diaphragm is vital for clinical outcomes.
Purpose of the Study:
- To investigate the combined effects of unilateral denervation and prolonged malnutrition on diaphragm muscle structure and function.
- To compare the effects of malnutrition alone, denervation alone, and combined denervation-malnutrition on diaphragm parameters.
Main Methods:
- Rats were divided into four groups: control, malnutrition (MN), denervation (DN), and combined denervation-malnutrition (DN-MN).
- Malnutrition was induced after denervation and lasted for 4 weeks.
- Diaphragm muscle weight, specific force, fatigue resistance, and fiber type proportions were analyzed.
Main Results:
- Both denervation and combined denervation-malnutrition led to a greater relative loss in diaphragm weight compared to body weight.
- Diaphragm specific force decreased by approximately 40% in DN and DN-MN groups, while remaining unaffected in the MN group.
- Diaphragm fatigue resistance improved in all experimental groups, with greater improvements in DN and DN-MN groups. Approximately 50% of diaphragm fibers became type IIc in DN and DN-MN groups.
Conclusions:
- Combined denervation and malnutrition significantly reduce diaphragm muscle's force-generating capacity due to decreased specific force and muscle cross-sectional area.
- While denervation alone caused atrophy in type IIb/x fibers, malnutrition and combined denervation-malnutrition led to atrophy across all fiber types.
- These findings highlight the detrimental interactive effects of denervation and malnutrition on diaphragm muscle.