Selective blockade of muscarinic receptor subtypes in the brain stem reticular formation in rats: effects on anesthetic requirements.
Muscarinic involvement in the modulation of general anesthesia was examined in the rat with a cannula implanted in the pontine reticular formation. Atropine microinjected into the reticular formation reversed the minimum alveolar concentration (MAC) reducing effect of carbachol on halothane anesthesia, but M(1) or M(3) antagonist had no effect. An M(2) antagonist reduced the MAC of halothane following saline and carbachol. The results suggest that any of the muscarinic receptor subtypes in this region do not independently mediate the cholinomimetic effect on halothane anesthesia.
Department of Anesthesiology and Critical Care Medicine, Gifu University School of Medicine, Gifu, Japan. ishizawa@mail.med.upenn.edu
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Ishizawa
D000759:Adjuvants, Anesthesia / Q000493:pharmacokinetics / Q000494:pharmacology; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000493:pharmacokinetics; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000493:pharmacokinetics / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000493:pharmacokinetics / Q000494:pharmacology; D006221:Halothane / Q000493:pharmacokinetics; D008297:Male; D008845:Microinjections; D018727:Muscarinic Antagonists / Q000494:pharmacology; D011149:Pons / Q000378:metabolism*; D020033:Protein Isoforms / Q000037:antagonists & inhibitors; D011650:Pulmonary Alveoli / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011976:Receptors, Muscarinic / Q000187:drug effects*; D012154:Reticular Formation / Q000187:drug effects / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology
D000759:Adjuvants, Anesthesia; D018685:Anesthetics, Inhalation; D018679:Cholinergic Agonists; D018727:Muscarinic Antagonists; D020033:Protein Isoforms; D011976:Receptors, Muscarinic; D012965:Sodium Chloride; D001285:Atropine; D002217:Carbachol; D006221:Halothane