Adrenergic receptors (also called adrenoceptors) are the receptors for the catecholamines adrenaline and noradrenaline (called epinephrine and norepinephrine in the United States). Adrenaline and noradrenaline play important roles in the control of blood pressure, myocardial contractile rate and force, airway reactivity, and a variety of metabolic and central nervous system functions.

Adrenergic receptors are members of the G-protein coupled receptor (GPCR) superfamily of membrane proteins. They share a common structure of seven putative transmembrane domains, an extracellular amino terminus, and a cytoplasmic carboxyl terminus.

Adrenoceptors are divided into three types: α₁, α₂ and β-adrenoceptors. Each type is further divided into at least three subtypes: α_1A, α_1B, α_1D, α_2A, α_2B, α_2C, β₁, β₂, β₃^1,2. Adrenoceptors are expressed in nearly all peripheral tissues and in the central nervous system^1,2.
 
The α_2B-adrenoceptor has a distinct pattern of expression within the brain, liver lung and kidney, and recent studies using the knock out mouse system have shown that disruption of this receptor indeed affects mouse viability³, blood pressure responses to α₂-adrenoceptor agonists³ and the hypertensive response to salt loading⁴.
 
Like the α_2A-adrenoceptor subtype, the α_2B-adrenoceptor undergoes short term agonist promoted desensitization⁵. This desensitization is due to the phosphorylation of the receptor by G-protein coupled receptor kinases (GRKs)⁶ which ultimately promotes uncoupling of the receptor from the G-protein subunit⁷.