title: Radioligand binding assay of M1-M5 muscarinic cholinergic receptor subtypes in human peripheral blood lymphocytes.
abstract: Analysis of lymphocyte muscarinic cholinergic receptors using quantitative techniques such as radioligand binding assay is made difficult due to the low density of these sites and the lack of subtype-specific selectivity of most available muscarinic ligands. In this study, a combined kinetic and equilibrium labeling technique recently developed for brain tissue was used for labeling the five muscarinic cholinergic receptor subtypes in intact human peripheral blood lymphocytes. No specific muscarinic M1 receptor binding was detectable in human peripheral blood lymphocytes using [3H]-pirenzepine as a ligand. Labeling of M2-M5 muscarinic receptors using [3H]N-methyl-scopolamine (NMS) by occluding various receptor subtypes with muscarinic antagonist and mamba venom resulted in the labeling of M2-M5 receptors in brain as well as in human peripheral blood lymphocytes. The relative density of different receptor subtypes was M3 > M5 > M4 > M2. The development of a reproducible technique for assaying muscarinic cholinergic receptor subtypes expressed by human peripheral blood lymphocytes may contribute to clarify their role in lymphocyte function.
authors.affiliation: Sezione di Anatomia Umana, dipartimento di Scienze Farmacologiche e Medicina Sperimentale, Università di Camerino, Italy.
authors.forename: S K
authors.initials: SK
authors.lastname: Tayebati
authors.forename: M
authors.initials: M
authors.lastname: Codini
authors.forename: V
authors.initials: V
authors.lastname: Gallai
authors.forename: F
authors.initials: F
authors.lastname: Mannino
authors.forename: L
authors.initials: L
authors.lastname: Parnetti
authors.forename: A
authors.initials: A
authors.lastname: Ricci
authors.forename: P
authors.initials: P
authors.lastname: Sarchielli
authors.forename: F
authors.initials: F
authors.lastname: Amenta
mesh_terms: D000328:Adult; D000818:Animals; D001285:Atropine / Q000378:metabolism / Q000494:pharmacology; D001345:Autoradiography; D001923:Brain Chemistry; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D008214:Lymphocytes / Q000737:chemistry* / Q000276:immunology*; D008297:Male; D018727:Muscarinic Antagonists / Q000378:metabolism / Q000494:pharmacology; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology; D010890:Pirenzepine / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding / Q000276:immunology; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D043643:Receptor, Muscarinic M1; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D043588:Receptor, Muscarinic M4; D043642:Receptor, Muscarinic M5; D011976:Receptors, Muscarinic / Q000032:analysis* / Q000276:immunology* / Q000378:metabolism; D014316:Tritium
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D018727:Muscarinic Antagonists; D010455:Peptides; D043643:Receptor, Muscarinic M1; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D043588:Receptor, Muscarinic M4; D043642:Receptor, Muscarinic M5; D011976:Receptors, Muscarinic; C089528:muscarinic toxin 3; D014316:Tritium; D010890:Pirenzepine; D001285:Atropine