Adrenergic receptors subtype characterization

Hillman KL, Doze VA, Porter JE. 2005. Functional characterization of the beta-adrenergic receptor subtypes expressed by CA1 pyramidal cells in the rat hippocampus. J Pharmacol Exp Ther 314 561-567. 

Of the nine adrenergic receptor subtypes, the a1D is the only one to be identified by cloning before characterization pharmacologically. Subsequently, it was shown that the so-called alc-receptor was actually the pharmacological a1A (64,65), and this was formalized by the IUPHAR Adrenergic Receptor Subcommittee (66). The current classification scheme includes the a1A, a1B, and a1D, but there is no alc. A fourth pharmacological subtype, the a1L, has been identified in vascular tissues from several species (67) but may represent a conformational state of the a1A-receptor (68). 

Morrow AL, Creese I. Characterization of a, adrenergic receptor subtypes in rat brain A reevaluation of [3H]WB4101 and [3H]prazosin binding. Mol Pharmacol 1986 29 321-330. 

Many physiological functions have been linked to specific subtypes of ar, o -, and (3-adrenergic receptors in various animal species. Because of the obvious reason of limited access, particularly regarding healthy tissue, similar progress for human adrenergic receptors has been slower and in many cases limited to the characterization of expression of RNA for the receptor subtypes. A more extensive characterization of protein and function for all the human adrenergic receptor subtypes is needed to identify specific targets for possible therapeutic intervention. 

In the central nervous system muscarinic acetylcholine receptors are more abundant than nicotinic receptors. They consist of single-chain proteins of mass 70 kDa. They are not ion channels but are 7-helix receptors homologous in sequence with P-adrenergic receptors (Fig. 11-6) and with rhodopsin.648 Five different subtypes (M1-M5) have been characterized. 

Adrenergic receptors (ARs) are the interface between the sympathetic nervous system and the cardiovascular system. ARs include two major subtypes, a and P, based on their pharmacological properties and molecular structure. The a-ARs consist of three ar AR subtypes and three o -ARs. P-ARs are also classified into three well-characterized subtypes Pb p2, and P3. Although they respond to the same hormones (norepinephrine and epinephrine), a- and P-ARs differ significantly in the types of cellular responses they mediate. 

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