α-Adrenoceptor-effector coupling: affinity states or heterogeneity of the α₂-adrenoceptor?

Receptor-effector coupling

At the present time there is substantial evidence supporting the concept of at least two major groups of α-adrenoceptors, which have been termed α₁ and α₂ [1]. Whereas α₁ and β₂ adrenoceptors are linked positively to adenylate cyclase, it seems likely that α₁- and α₂-adrenoceptors possess different mechanisms for signal transduction.