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Expiratory abdominal muscle activity during ventilatory chemostimulation in piglets
J F Watchko1, T L O'Day, B S Brozanski
1Department of Pediatrics, University of Pittsburgh School of Medicine, Magee-Womens Hospital, Pennsylvania 15213.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 1, 1990
Summary
Newborn piglets show abdominal muscle activity during normal breathing. Both high CO2 and low O2 increase this activity, but only high CO2 causes a lasting increase, suggesting complex respiratory control.
Area of Science:
- Physiology
- Respiratory Control
- Neonatal Physiology
Background:
- Abdominal muscle electromyographic (EMG) activity is crucial for respiration.
- Understanding neonatal respiratory control mechanisms is vital for clinical care.
Purpose of the Study:
- To investigate abdominal muscle EMG activity in newborn piglets under various respiratory conditions.
- To assess the influence of vagal afferent pathways on these responses.
Main Methods:
- Measured minute electromyographic (EMG) activity of abdominal muscles in anesthetized newborn piglets.
- Exposed piglets to eupnea, hyperoxic hypercapnia, and hypoxia.
- Evaluated the effect of bilateral cervical vagotomy on EMG activity.
Main Results:
- Phasic expiratory abdominal EMGab was observed during eupnea in most piglets.
- Hypercapnia sustainedly augmented minute EMGab, while hypoxia caused a transient increase followed by a decrease.
- Vagotomy reduced baseline abdominal EMGab but did not alter the response to chemostimulation.
Conclusions:
- Expiration in anesthetized piglets involves phasic abdominal EMGab.
- Both hypercapnia and hypoxia modulate abdominal muscle activity, with hypercapnia showing sustained effects.
- Vagal afferents influence baseline abdominal muscle activity, but extravagal mechanisms primarily drive responses to chemostimulation.