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Anesthetic effects on phasic genioglossus activity and the negative pressure reflex in the rat
Author(s) -
Chamberlin Nancy Louise,
Fassbender Philipp,
Malhotra Atul,
Jordan Amy S.,
White David P
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1294-b
Subject(s) - genioglossus , isoflurane , anesthesia , anesthetic , medicine , vagotomy , propofol , pentobarbital , vagus nerve , ventilation (architecture) , airway , stimulation , mechanical engineering , engineering
The genioglossus muscle (GG) is an upper airway dilator which protects pharyngeal patency in humans. General anesthesia typically impairs airway stability and decreases phasic GG EMG in vagotomized, ventilated rats. However, some anesthetics may increase GG EMG in spontaneously‐breathing rats. The mechanisms by which anesthetics affect GG activity have not been studied systematically. The ED50 for pentobarbital, propofol, or isoflurane was estimated in 63 rats. After tracheostomy to isolate the upper airway, phasic GG EMG and responses to upper airway negative pressure (NPR) were measured with and without blood pressure or end‐tidal CO2 normalized, and also in vagotomized or Kolliker‐Fuse nucleus (KF) lesioned animals. Phasic GG amplitude was anesthetic‐dependent; with isoflurane mean levels were >250% versus pentobarbital and propofol at equianalgesic doses. Isoflurane (1‐2 vol%) produced dose‐dependent increases in phasic GG activity but inhibited the NPR, effects that persisted with normalized blood pressure and/or end‐tidal CO2, or KF lesion. Effects of isoflurane on respiratory pattern resembled those of cervical vagotomy: increased T I and V T , and decreased RR. Bilateral cervical vagotomy, but not superior laryngeal nerve section, blocked effects of isoflurane on GG activity. Thus isoflurane may increase GG activity by inhibition of bronchopulmonary sensory feedback.