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Expiratory neural activities in gasping.
W M St John1, D Zhou, R F Fregosi
1Department of Physiology, Dartmouth Medical School, Hanover, New Hampshire 03756.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|January 1, 1989
Summary
Gasping significantly reduces expiratory neural activities in cats, particularly in spinal nerves, while inspiratory activities increase. This highlights fundamental differences between gasping and normal breathing patterns.
Area of Science:
- Neuroscience
- Respiratory Physiology
Background:
- Breathing control involves complex neural networks.
- Eupnea (normal breathing) and gasping represent distinct respiratory patterns.
Purpose of the Study:
- To characterize expiratory-related neural activities during eupnea and gasping.
- To compare neural discharge patterns in phrenic, spinal, and laryngeal nerves between breathing states.
Main Methods:
- Recordings from phrenic, spinal intercostal/abdominal, and recurrent laryngeal nerves in decerebrate, vagotomized cats.
- Induction of gasping via brainstem freezing, asphyxia, anoxia, or basilar artery ligation.
- Utilized servo-ventilation in intact vagi cats to mimic lung inflation with phrenic activity.
Main Results:
- Gasping increased peak phrenic activity and inspiratory nerve activities.
- Expiratory activities in spinal and laryngeal nerves were significantly reduced during gasping.
- Spinal nerve expiratory activity reduction was more pronounced than in laryngeal nerves.
Conclusions:
- Gasping exhibits markedly reduced expiratory neural output compared to eupnea.
- Neural control of breathing differs fundamentally between eupneic and gasping states.
- Findings challenge existing concepts of respiratory pattern generation.