Correlation between degree of inhibition of parasympathetic reflex vasodilation and MAC value for various inhalation anesthetics.
Parasympathetic reflex vasodilation was elicited in the lower lip by stimulation of the central cut end of the lingual nerve in urethane plus alpha-chloralose-anesthetized, vago-sympathectomized cats. A dose-related inhibition of this response was induced by the inhalation anesthetics isoflurane, halothane, sevoflurane, and enflurane, the ID50 values being 0.94%, 0.82%, 1.74%, and 2.0%, respectively. These results indicate that the ID50 value is approximately two-thirds of the published MAC (for isoflurane, halothane, sevoflurane, and enflurane, 1.6%, 1.2%, 2.6%, and 2.4%, respectively) value for such anesthetics, suggesting that parasympathetic reflex vasodilation is more susceptible than somato-somatic reflexes to inhibition by inhalation anesthetics.
Department of Physiology, Tohoku University School of Dentistry, Sendai, Japan. izumi@physiol.dent.tohoku.ac.jp
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D000758:Anesthesia; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D002415:Cats; D003714:Denervation; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004737:Enflurane / Q000494:pharmacology; D005260:Female; D006221:Halothane / Q000494:pharmacology; D007530:Isoflurane / Q000494:pharmacology; D008036:Lingual Nerve / Q000502:physiology; D008046:Lip / Q000098:blood supply / Q000294:innervation; D008297:Male; D008452:Maximum Allowable Concentration; D008738:Methyl Ethers / Q000494:pharmacology; D010275:Parasympathetic Nervous System / Q000187:drug effects* / Q000502:physiology; D012018:Reflex / Q000187:drug effects*; D000077149:Sevoflurane; D013562:Sympathectomy; D014628:Vagotomy; D014630:Vagus Nerve / Q000502:physiology / Q000601:surgery; D014664:Vasodilation / Q000187:drug effects*
D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D004737:Enflurane; D007530:Isoflurane; D006221:Halothane