Mitchelson_1989_Clin.Exp.Pharmacol.Physiol_16_523

1. Several selective antagonists are available to differentiate between muscarinic receptors. 2. Further subdivision of M1 and M2 muscarinic receptors appears possible and is supported by studies with cloned receptors. 3. Reasons for differences between affinity constants determined in functional and binding studies and whether receptor subtypes couple exclusively with a particular cellular mechanism are still to be determined.