title: Muscarinic cholinergic binding in rat brain.
abstract: Binding sites with high affinity and specificity for [(3)H]quinuclidinyl benzilate (QNB) are present in homogenates of rat brain. The characteristics of the binding sites resemble those of muscarinic cholinergic receptors. Specific binding is saturable with respect to [(3)H]QNB and tissue concentration and is time-, temperature-, and pH-dependent. The bimolecular rate of association (2.0 x 10(8) M(-1) min(-1)) and dissociation (1.2 x 10(-2) min(-1)) at 35 degrees indicate a dissociation constant of 60 pM and a density of 65 pmol/g of brain. Muscarinic antagonists and agonists displace specific [(3)H]QNB binding, while nicotinic and non-cholinergic drugs possess little affinity for [(3)H]QNB-binding sites.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001115:Arecoline / Q000494:pharmacology; D001285:Atropine / Q000494:pharmacology; D001561:Benzilates / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D001977:Brompheniramine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002744:Chlorpheniramine / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008688:Methacholine Compounds / Q000494:pharmacology; D008861:Microsomes / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D010095:Oxotremorine / Q000378:metabolism*; D010862:Pilocarpine / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D011812:Quinuclidines / Q000378:metabolism*; D051381:Rats; D011950:Receptors, Cholinergic; D012601:Scopolamine / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors; D014316:Tritium
chemical_list: D001561:Benzilates; D008688:Methacholine Compounds; D000644:Quaternary Ammonium Compounds; D011812:Quinuclidines; D011950:Receptors, Cholinergic; D010862:Pilocarpine; D014316:Tritium; D002744:Chlorpheniramine; D001115:Arecoline; D010095:Oxotremorine; D001285:Atropine; D002217:Carbachol; D012601:Scopolamine; D001977:Brompheniramine; D000109:Acetylcholine