Differential interactions of muscarinic drugs with binding sites of [3H]pirenzepine and [3H]quinuclidinyl benzilate in rat brain tissue

• Published in: Life sciences (1973) Vol. 40; no. 20; p. 1981
• Main Authors: Tonnaer, J A, van Vugt, M A, de Boer, T, de Graaf, J S
• Format: Journal Article
• Language: English
• Published: Netherlands 18.05.1987
• Subjects: Animals; Binding Sites; Binding, Competitive; Brain Chemistry; Cell Membrane - metabolism; Male; Parasympatholytics - metabolism; Parasympathomimetics - metabolism; Pirenzepine - metabolism; Protein Binding; Quinuclidines - metabolism; Quinuclidinyl Benzilate - metabolism; Rats; Rats, Inbred Strains; Receptors, Muscarinic - classification; Receptors, Muscarinic - metabolism
• DOI: 10.1016/0024-3205(87)90287-6
• ISSN: 0024-3205

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.