Consequences of periodic augmented breaths on tongue muscle activities in hypoxic rats

Patrick L. Janssen, James S. Williams, Ralph F. Fregosi

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

This study was designed to investigate the influence of hypoxia-evoked augmented breaths (ABs) on respiratory-related tongue protrudor and retractor muscle activities and inspiratory pump muscle output. Genioglossus (GG) and hyoglossus (HG) electromyogram (EMG) activities and respiratory-related tongue movements were compared with peak esophageal pressure (Pes; negative change in pressure during inspiration) and minute Pes (Pes x respiratory frequency = Pes/min) before and after ABs evoked by sustained poikilocapnic, isocapnic, and hypercapnic hypoxia in spontaneously breathing, anesthetized rats. ABs evoked by poikilocapnic and isocapnic hypoxia triggered long- lasting (duration at least 10 respiratory cycles) reductions in GG and HG EMG activities and tongue movements relative to pre-AB levels, but Pes was reduced transiently (duration of <10 duration cycles) after ABs. Adding 7% CO2 to the hypoxic inspirate had no effect on the frequency of evoked ABs, but this prevented long-term declines in tongue muscle activities. Bilateral vagotomy abolished hypoxia-induced ABs and stabilized drive to the tongue muscles during each hypoxic condition. We conclude that, in the rat, hypoxia- evoked ABs 1) elicit long-lasting reduction in protrudor and retractor tongue muscle activities, 2) produce short-term declines in inspiratory pump muscle output, and 3) are mediated by vagal afferents. The more prolonged reductions in pharyngeal airway vs. pump muscle activities may lead to upper airway narrowing or collapse after spontaneous ABs.

Original languageEnglish (US)
Pages (from-to)1915-1923+1897
JournalJournal of Applied Physiology
Volume88
Issue number5
DOIs
StatePublished - May 2000

Keywords

  • Genioglossus
  • Hyoglossus
  • Mechanisms
  • Sighs

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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