Beta-1, Beta-2, and Beta-3 adrenergic receptors (Beta-1 AR, Beta-2 AR, Beta-3 AR)

Beta-adrenergic receptors are transmembrane G protein-coupled receptors critical to sympathetic nervous system signaling, mediating responses to catecholamines such as epinephrine and norepinephrine. There are three main subtypes: beta-1 adrenergic receptor (predominant in cardiac tissue and key for increasing heart rate and contractility), beta-2 adrenergic receptor (found mainly in smooth muscle, especially airways, mediating bronchodilation and metabolic effects), and beta-3 adrenergic receptor (primarily in adipose tissue and bladder, regulating lipolysis and bladder relaxation). Each receptor subtype is encoded by a distinct gene and has unique physiological roles, disease associations, and drug interaction profiles.

Other names

β1 adrenergic receptorβ2 adrenergic receptorβ3 adrenergic receptorAdrenoceptors (collective)Beta-adrenoceptorBeta-adrenergic receptor

Agonists activate β-ARs, increasing cAMP and triggering downstream physiological effects (e.g., increased heart rate, bronchodilation, lipolysis). Antagonists block β-ARs, inhibiting sympathetic effects (e.g., reducing heart rate, relaxing smooth muscle, lowering blood pressure). Beta-3 agonists (mirabegron) relax bladder muscle. Beta-2 agonists cause bronchodilation. Beta-1 antagonists provide cardioselective beta-blockade.