title: Himbacine recognizes a high affinity subtype of M2 muscarinic cholinergic receptors in the rat cerebral cortex.
abstract: The in vitro receptor binding properties of a muscarinic antagonist himbacine have been studied in rat cerebral cortical, cardiac and ileal membranes. Himbacine displayed high affinity (KH = 2.94 nM) for 19%, and low affinity (KL = 71.2 nM) for the remaining muscarinic receptors in rat cerebral cortex. This high affinity of himbacine agrees with its affinity for the 62% of cerebral cortical [3H]AF-DX 116 binding sites (KH = 2.30 nM). The affinity of himbacine for cardiac receptors (Ki = 9.06 nM) and ileal receptors (Ki = 12.4 nM) was the same. Therefore, himbacine appears to be a high-affinity M2-selective ligand which recognizes a subtype of M2 receptors in the cerebral cortex.
authors: Department of Pharmacology, University of Arizona Health Sciences Center, Tucson 85724.
authors: J X
authors: JX
authors: Wang
authors: W R
authors: WR
authors: Roeske
authors: W
authors: W
authors: Wang
authors: H I
authors: HI
authors: Yamamura
mesh_terms: D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D005663:Furans; D007082:Ileum / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009281:Naphthalenes; D009928:Organ Specificity; D010276:Parasympatholytics / Q000494:pharmacology*; D010880:Piperidines; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000470:Alkaloids; D005663:Furans; D009281:Naphthalenes; D010276:Parasympatholytics; D010880:Piperidines; D011976:Receptors, Muscarinic; C048172:himbacine