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Nitric oxide synthase in aging rat skeletal muscle
C R Richmonds1, K Boonyapisit, L L Kusner
1Department of Neurology, Department of Veterans Affairs Medical Center in Cleveland, Case Western Reserve University School of Medicine, University Hospitals of Cleveland, Ohio 44106, USA.
Mechanisms of Ageing and Development
|November 27, 1999
Summary
Aging reduces nitric oxide synthase (NOS) activity in rat skeletal muscles, impacting muscle function but not necessarily increasing oxidative stress. This age-related decline in NOS is more significant for metabolism than free radical damage.
Area of Science:
- Muscle physiology
- Neuroscience
- Aging research
Background:
- Neuronal nitric oxide synthase (NOS) is abundant in skeletal muscle, influencing contractility, glucose uptake, and oxidative stress.
- Aging is associated with changes in muscle function and potentially altered NO signaling.
Purpose of the Study:
- To investigate the age-related changes in NOS activity and expression in different rat skeletal muscle types.
- To determine if reduced NOS activity with age correlates with increased lipid peroxidation, an indicator of oxidative damage.
Main Methods:
- Assessed NOS activity and quantified NOS-containing fibers in extensor digitorum longus (EDL), soleus, and diaphragm muscles of 8 and 24-month-old rats.
- Measured lipid peroxidation levels using malonaldehyde equivalents to assess oxidative injury.
Main Results:
- NOS activity and the percentage of NOS-containing fibers decreased significantly with age across all examined muscle groups.
- Lipid peroxidation increased with age in EDL, decreased in diaphragm, and showed no significant change in soleus, indicating a complex relationship with NOS reduction.
- The reduction in NOS activity with aging did not consistently correlate with increased lipid peroxidation across all muscle types.
Conclusions:
- The age-associated decline in skeletal muscle NOS activity is significant for muscle metabolism and force production.
- Reduced NOS in aging muscle appears to have limited direct implications for free radical metabolism, as evidenced by variable lipid peroxidation levels.