title: Differential interactions of muscarinic drugs with binding sites of [3H]pirenzepine and [3H]quinuclidinyl benzilate in rat brain tissue.
abstract: Some atypical muscarinic drugs were compared with classical drugs with respect to inhibition of specific binding of [3H]pirenzepine ([3H]PZ) and [3H]quinuclidinyl benzilate ([3H]QNB) to membrane preparations of rat brain. The interactions of the agonists McN-A343 and carbachol with [3H]QNB at muscarinic sites in brain stem preparations were differently modulated in the presence of an excess of PZ. Moreover, McN-A343 exhibited a preferential affinity for [3H]PZ sites in whole brain membranes whereas carbachol bound with high affinity to [3H]QNB sites in brain stem preparations. Various muscarinic agonists and antagonists displayed different affinity patterns in the [3H]PZ and [3H]QNB binding. These data are indicative of two populations of pharmacologically distinguishable binding sites and support the concept of muscarinic receptor heterogeneity in rat brain.
mesh_terms: D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D001923:Brain Chemistry; D002462:Cell Membrane / Q000378:metabolism; D008297:Male; D010276:Parasympatholytics / Q000378:metabolism*; D010277:Parasympathomimetics / Q000378:metabolism*; D010890:Pirenzepine / Q000378:metabolism*; D011485:Protein Binding; D011812:Quinuclidines / Q000378:metabolism*; D011813:Quinuclidinyl Benzilate / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000145:classification / Q000378:metabolism*
chemical_list: D010276:Parasympatholytics; D010277:Parasympathomimetics; D011812:Quinuclidines; D011976:Receptors, Muscarinic; D010890:Pirenzepine; D011813:Quinuclidinyl Benzilate