Effect of hypoxia on expiratory muscle activity in fetal sheep

John M. Bissonnette, Alan (Roger) Hohimer, Sharon J. Knopp

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The fetal respiratory response to acute hypoxia is characterized by depression, often to apnea. This study examined the effect of hypoxia on the electromyogram (EMG) of the thyroarytenoid (TA) muscle. Under anesthesia catheters were placed in the fetal sheep carotid artery, fourth cerebral ventricle, trachea and amniotic fluid and wires sewn into the diaphragm and TA muscle. During normoxic episodes of slow fetal breathing (2 from ∼20 mmHg to ∼13 mmHg resulted in arrest of diaphragm EMG and tonic TA activity. Instillation of the (R,S)- -amino-3- hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) ionotrophic glutamate receptor antagonist 2,3-dihydro-6-nitro-7-sulphamoyl-benzo(f) quinoxaline (NBQX) into the cerebrospinal fluid (CSF) of the fourth ventricle abolished tracheal pressure deflections and diaphragmatic EMG activity. Tonic TA activity, however, could still be evoked by hypoxia. These results indicate that fetal post-I motoneurons are not inhibited by moderate hypoxia and that their tonic activity may be due to a loss of inhibitory input.

Original languageEnglish (US)
Pages (from-to)110-114
Number of pages5
JournalRespiratory Physiology and Neurobiology
Volume171
Issue number2
DOIs
StatePublished - Apr 30 2010

Fingerprint

Fetal Movement
Sheep
Electromyography
Laryngeal Muscles
Fourth Ventricle
Muscles
Diaphragm
Cerebral Ventricles
Excitatory Amino Acid Antagonists
Motor Neurons
Apnea
Amniotic Fluid
Trachea
Carotid Arteries
Cerebrospinal Fluid
Respiration
Catheters
Anesthesia
Pressure
Acids

Keywords

  • Amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA)
  • Hypoxic ventilatory response
  • Thyroarytenoid muscle

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Neuroscience(all)
  • Medicine(all)

Cite this

Effect of hypoxia on expiratory muscle activity in fetal sheep. / Bissonnette, John M.; Hohimer, Alan (Roger); Knopp, Sharon J.

In: Respiratory Physiology and Neurobiology, Vol. 171, No. 2, 30.04.2010, p. 110-114.

Research output: Contribution to journalArticle

Bissonnette, John M. ; Hohimer, Alan (Roger) ; Knopp, Sharon J. / Effect of hypoxia on expiratory muscle activity in fetal sheep. In: Respiratory Physiology and Neurobiology. 2010 ; Vol. 171, No. 2. pp. 110-114.
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