Beta-1 adrenergic receptor, Beta-2 adrenergic receptor, Alpha-1 adrenergic receptor (β1-AR, β2-AR, α1-AR)

Beta-1, Beta-2, and Alpha-1 adrenergic receptors are members of the adrenergic receptor subfamily of G protein-coupled receptors. These receptors mediate the effects of the endogenous catecholamines epinephrine and norepinephrine, acting throughout the body to regulate cardiovascular function, airway tone, metabolism, and neuronal signaling. Beta-1 adrenergic receptors are highly expressed in the heart and kidneys, Beta-2 in the lungs and vascular smooth muscle, and Alpha-1 in vascular and other smooth muscle. Their differential tissue distribution underlies their distinct physiological and pharmacological roles. They are major therapeutic targets in cardiovascular and respiratory disease, with drugs acting as either agonists or antagonists to modify heart rate, contractility, airway caliber, and vascular tone.

Other names

Beta-adrenergic receptor (for β1, β2 together)Alpha-adrenergic receptor (for α1 when not specifying subtype)β-adrenoceptorβ1-adrenoceptorβ2-adrenoceptorα1-adrenoceptor

Agonists activate G-protein signaling, increasing cAMP (β) or IP3/DAG (α1), resulting in increased heart rate/contractility (β1), smooth muscle relaxation (β2), or vasoconstriction (α1). Antagonists (blockers) inhibit these effects, reducing blood pressure, heart rate, or relaxing smooth muscles.