Effects of inhalation anesthetics on parasympathetic reflex vasodilation in the lower lip and palate of the cat.
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 gamma-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 structure.
Izumi
H
H
Department of Physiology, Tohoku University School of Dentistry, Sendai, Japan.
Ito
Y
Y
Sato
M
M
Karita
K
K
Iwatsuki
N
N
D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D002415:Cats; D003655:Decerebrate State; D004558:Electric Stimulation; D004987:Ethers / Q000494:pharmacology*; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D005725:Ganglia, Autonomic / Q000187:drug effects / Q000502:physiology; D005730:Ganglionic Blockers / Q000494:pharmacology; D006221:Halothane / Q000494:pharmacology; D018738:Hexamethonium / Q000494:pharmacology; D007530:Isoflurane / Q000494:pharmacology; D008036:Lingual Nerve / Q000502:physiology; D008046:Lip / Q000098:blood supply* / Q000294:innervation; D008297:Male; D008738:Methyl Ethers; D009020:Morphine / Q000494:pharmacology; D009609:Nitrous Oxide / Q000494:pharmacology; D010159:Palate / Q000098:blood supply* / Q000294:innervation; D010275:Parasympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D010852:Picrotoxin / Q000494:pharmacology; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D000077149:Sevoflurane; D013562:Sympathectomy; D014059:Tongue / Q000098:blood supply* / Q000294:innervation; D014628:Vagotomy; D014664:Vasodilation / Q000502:physiology*
D018685:Anesthetics, Inhalation; D004987:Ethers; D018756:GABA Antagonists; D005730:Ganglionic Blockers; D006221:Halothane; D018738:Hexamethonium; D007530:Isoflurane; D008738:Methyl Ethers; D009020:Morphine; D009609:Nitrous Oxide; D010852:Picrotoxin; D000077149:Sevoflurane