Selective labelling of M1-receptors in autonomic ganglia with 3H-pirenzepine.
Using the classical muscarinic antagonist 3H-N-methyl-scopolamine as radioligand and unlabelled pirenzepine (PZ) as displacing agent, a heterogeneous muscarinic receptor population consisting of about 70% M1-receptors and 30% M2-receptor, can be demonstrated in crude membranes of calf sympathetic ganglia. In the same preparation only low and variable specific binding is detectable when 3H-PZ is used as marker ligand. The situation clearly improves when synaptosomes are prepared from the ganglia. Then binding of 3H-PZ can be measured with a favourable specific to non specific binding ratio and with features compatible with the selective labelling of ganglionic M1-receptor sites. It is concluded that the 3H-PZ binding assay in synaptosomes of autonomic ganglia is a novel method for the characterization of the peripheral M1-receptor.
D000818:Animals; D001285:Atropine / Q000378:metabolism; D001570:Benzodiazepinones / Q000378:metabolism*; D001667:Binding, Competitive; D002417:Cattle; D005725:Ganglia, Autonomic / Q000378:metabolism*; D005728:Ganglia, Sympathetic / Q000378:metabolism; D066298:In Vitro Techniques; D019832:N-Methylscopolamine; D010890:Pirenzepine; D011813:Quinuclidinyl Benzilate; D011869:Radioligand Assay; D011976:Receptors, Muscarinic / Q000145:classification / Q000378:metabolism*; D012602:Scopolamine Derivatives / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism
D001570:Benzodiazepinones; D011976:Receptors, Muscarinic; D012602:Scopolamine Derivatives; D010890:Pirenzepine; D011813:Quinuclidinyl Benzilate; D001285:Atropine; D019832:N-Methylscopolamine