Choo_1985_J.Pharm.Pharmacol_37_656

The ability of the muscarinic receptor antagonists fenipramide, 4-diphenylacetoxy-N-methyl piperidine methiodide (4-DAMP) and secoverine to displace [3H]QNB binding was correlated with the inhibition of responses of cholinomimetics at muscarinic receptors in the atria and ileal longitudinal muscle of the guinea-pig. Fenipramide and 4-DAMP exhibited a 2-4 fold higher affinity for muscarinic receptors in ileal longitudinal muscle in both types of experiments. Secoverine exhibited no difference in affinity in the two tissues.