Effects of inhalation anesthetics on parasympathetic reflex vasodilation in the lower lip and palate of the cat

Hiroshi Izumi, Yutaka Ito, Minoru Sato, Keishiro Karita, Naofumi Iwatsuki

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22 Citations (Scopus)

Abstract

The present experiments were designed to examine the effects of inhalation anesthetics (isoflurane, halothane, and sevoflurane) on the parasympathetic reflex vasodilation in the lower lip and palate elicited by electrical stimulation of the central cut end of the lingual nerve in vagosympathectomized cats. Isoflurane (1.5%), halothane (1.0%), and sevoflurane (2.5%), each at a concentration of 1.0 minimum alveolar concentration, markedly suppressed the evoked blood flow increases in the lower lip, whereas nitrous oxide (70% in 30% oxygen) and morphine (2 mg/kg iv) did not. Prior administration of picrotoxin, a γ-aminobutyric acid (GABA) antagonist (2 mg/kg iv), reversed the inhibitory effect of isoflurane on the parasympathetic reflex response. Decerebration had no significant effect on the isoflurane-induced inhibition. These findings suggest that there is a GABA-mediated suppressive mechanism acting on this parasympathetic reflex response; the sites at which inhalation anesthetics exert such an inhibitory action could be in the midbrain, pons, or medulla, but not in the hypothalamus or higher structures.

Original languageEnglish
Pages (from-to)R168-R174
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume273
Issue number1 42-1
DOIs
Publication statusPublished - 1997 Jul

Keywords

  • γ-aminobutyric acid

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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