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The changes in neuromuscular excitability with normobaric hyperoxia in humans
Christelle Brerro-Saby1, Stéphane Delliaux, Jean Guillaume Steinberg
1Faculté de Médecine, Université de la Méditerranée, UMR MD2P2COE Boulevard Pierre Dramard, Marseille 13916, Cedex 20, France.
Experimental Physiology
|August 18, 2009
Summary
Normobaric hyperoxia enhances neuromuscular excitability and nerve conduction but reduces proprioceptive reflexes. This dual effect, linked to oxidative stress, impacts muscle afferents and spinal reflexes during pure oxygen breathing.
Area of Science:
- Physiology
- Neuroscience
- Biochemistry
Background:
- Hyperbaric hyperoxia has shown effects on neuromuscular excitability.
- Normobaric hyperoxia is common in anesthesia and resuscitation.
- The impact of normobaric hyperoxia on neuromuscular function requires further investigation.
Purpose of the Study:
- To investigate the effects of normobaric hyperoxia on neuromuscular excitability.
- To explore the consequences of pure oxygen breathing on the proprioceptive reflex loop.
- To assess hyperoxia-induced oxidative stress markers.
Main Methods:
- Healthy volunteers underwent 50 minutes of pure oxygen breathing.
- Measurements included neuromuscular conduction time (CT), M-wave amplitude, H reflex, and tonic vibratory response (TVR).
- Blood markers for lipid peroxidation (TBARS) and antioxidant response (RAA) were analyzed.
Main Results:
- Hyperoxia increased M-wave amplitude, shortened CT and H reflex latency, and augmented H reflex amplitude.
- Tonic vibratory response (TVR) significantly decreased.
- Increased TBARS and decreased RAA levels indicated oxidative stress.
Conclusions:
- Normobaric hyperoxia exhibits dual effects: facilitating muscle membrane excitability, nerve conduction, and spinal reflexes.
- Hyperoxia reduces the gain of the proprioceptive reflex loop.
- Activation of group IV muscle afferents and oxidative stress may explain TVR depression.
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