SUBCLASSIFICATION OF PERIPHERAL DOPAMINE-RECEPTORS

1 There is convincing evidence to suggest that two DA-receptor subtypes exist in the periphery, that can at best be differentiated by the potency of the antagonists SCH 23390 and domperidone: at DA-1 receptors the order of potency is SCH 23390 >>> domperidone, at DA-2 receptors it is domperidone >>> SCH 23390. 2 As in the adrenergic, muscarinic or 5-HT-receptor field, future studies employing both molecular biology and pharmacological approaches will show whether such a subclassification is sufficient to explain all peripheral effects of DA or whether DA-1 and DA-2 receptors have to be subdivided into further subtypes.