No evidence for long-term facilitation after episodic hypoxia in spontaneously breathing, anesthetized rats

Patrick L. Janssen, Ralph F Fregosi

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

Repeated electrical or hypoxic stimulation of peripheral chemoreceptors has been shown to cause a persistent poststimulus increase in respiratory motoneuron activity, termed long-term facilitation (LTF). LTF after episodic hypoxia has been demonstrated most consistently in anesthetized, vagotomized, paralyzed, artificially ventilated rats. Evidence for LTF in spontaneously breathing animals and humans after episodic hypoxia is equivocal and may have been influenced by the awake state of the subjects in these studies. The present study was designed to test the hypothesis that LTF is evoked in respiratory-related tongue muscle and inspiratory pump muscle activities after episodic hypoxia in 10 spontaneously breathing, anesthetized, vagotomized rats. The animals were exposed to three (5-min) episodes of isocapnic hypoxia, separated by 5 min of hyperoxia (50% inspired oxygen). Genioglossus, hyoglossus, and inspiratory intercostal EMG activities, along with respiratory-related tongue movements and esophageal pressure, were recorded before, during, and for 60 min after the end of episodic isocapnic hypoxia. We found no evidence for LTF in tongue muscle (genioglossus, hyoglossus) or inspiratory pump muscle (inspiratory intercostal) activities after episodic hypoxia. Rather, the primary poststimulus effect of episodic hypoxia was diminished respiratory frequency, which contributed to a reduction in ventilatory drive.

Original languageEnglish (US)
Pages (from-to)1345-1351
Number of pages7
JournalJournal of Applied Physiology
Volume89
Issue number4
StatePublished - 2000

Fingerprint

Respiration
Tongue
Muscles
Intercostal Muscles
Hyperoxia
Motor Neurons
Hypoxia
Oxygen
Pressure

Keywords

  • Control of breathing
  • Esophageal pressure
  • Genioglossus
  • Hyoglossus
  • Intercostals

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

No evidence for long-term facilitation after episodic hypoxia in spontaneously breathing, anesthetized rats. / Janssen, Patrick L.; Fregosi, Ralph F.

In: Journal of Applied Physiology, Vol. 89, No. 4, 2000, p. 1345-1351.

Research output: Contribution to journalArticle

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