Alpha 4 beta 2 neuronal nicotinic acetylcholine receptors in the central nervous system are inhibited by isoflurane and propofol, but alpha 7-type nicotinic acetylcholine receptors are unaffected. 1997

P Flood, and J Ramirez-Latorre, and L Role
Columbia University, Department of Anesthesiology, New York, New York 10032, USA. PDF3@Columbia.edu

BACKGROUND The mechanisms of action of general anesthetics are not completely understood. Many general anesthetics are reported to potentiate gamma-aminobutyric acid (GABAA) and glycine receptors in the central nervous system (CNS) and to inhibit the muscle-type nicotinic acetylcholine receptor (nAChR). The effects of general anesthetics on another family of ligand-gated ion channel in the CNS, the nAChRs, have not been defined. METHODS Two types of CNS acetylcholine receptor, the alpha 4 beta 2 receptor or the alpha 7 homomeric receptor, were expressed heterologously in Xenopus laevis oocytes. Using the standard two-microelectrode voltage-clamp technique, peak acetylcholinegated current was measured before and after coapplication of isoflurane or propofol. RESULTS Coapplication of either isoflurane or propofol with acetylcholine resulted in potent, dose-dependent inhibition of the alpha 4 beta 2 receptor current with median inhibitory concentrations of 85 and 19 microM, respectively. The inhibition of the alpha 4 beta 2 receptor by both isoflurane and propofol appears to be competitive with respect to acetylcholine. The alpha 7 receptor current was not effected by either anesthetic. CONCLUSIONS The CNS-type nAChRs are differentially affected by isoflurane and propofol. The alpha 4 beta 2 receptor is affected by isoflurane more potently than the most sensitive GABAA or glycine receptor that has been reported, whereas the alpha 7 homomeric receptor is not affected by either anesthetic. Inhibition of specific subtypes of nAChRs in the CNS, along with potentiation of GABAA and glycine receptors, may contribute to the effects and side effects of general anesthetics.

UI MeSH Term Description Entries
D007530 Isoflurane A stable, non-explosive inhalation anesthetic, relatively free from significant side effects.
D011978 Receptors, Nicotinic One of the two major classes of cholinergic receptors. Nicotinic receptors were originally distinguished by their preference for NICOTINE over MUSCARINE. They are generally divided into muscle-type and neuronal-type (previously ganglionic) based on pharmacology, and subunit composition of the receptors. Nicotinic Acetylcholine Receptors,Nicotinic Receptors,Nicotinic Acetylcholine Receptor,Nicotinic Receptor,Acetylcholine Receptor, Nicotinic,Acetylcholine Receptors, Nicotinic,Receptor, Nicotinic,Receptor, Nicotinic Acetylcholine,Receptors, Nicotinic Acetylcholine
D001921 Brain The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM. Encephalon
D002645 Chickens Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA. Gallus gallus,Gallus domesticus,Gallus gallus domesticus,Chicken
D004305 Dose-Response Relationship, Drug The relationship between the dose of an administered drug and the response of the organism to the drug. Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D005260 Female Females
D000777 Anesthetics Agents capable of inducing a total or partial loss of sensation, especially tactile sensation and pain. They may act to induce general ANESTHESIA, in which an unconscious state is achieved, or may act locally to induce numbness or lack of sensation at a targeted site. Anesthetic,Anesthetic Agents,Anesthetic Drugs,Anesthetic Effect,Anesthetic Effects,Agents, Anesthetic,Drugs, Anesthetic,Effect, Anesthetic,Effects, Anesthetic
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D014982 Xenopus laevis The commonest and widest ranging species of the clawed "frog" (Xenopus) in Africa. This species is used extensively in research. There is now a significant population in California derived from escaped laboratory animals. Platanna,X. laevis,Platannas,X. laevi
D015742 Propofol An intravenous anesthetic agent which has the advantage of a very rapid onset after infusion or bolus injection plus a very short recovery period of a couple of minutes. (From Smith and Reynard, Textbook of Pharmacology, 1992, 1st ed, p206). Propofol has been used as ANTICONVULSANTS and ANTIEMETICS. Disoprofol,2,6-Bis(1-methylethyl)phenol,2,6-Diisopropylphenol,Aquafol,Diprivan,Disoprivan,Fresofol,ICI-35,868,ICI-35868,Ivofol,Propofol Abbott,Propofol Fresenius,Propofol MCT,Propofol Rovi,Propofol-Lipuro,Recofol,2,6 Diisopropylphenol,ICI 35,868,ICI 35868,ICI35,868,ICI35868

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