Adrenergic receptor (alpha and beta subtypes)

Alpha- and beta-adrenergic receptors are closely related families of G protein-coupled receptors that mediate the effects of the endogenous catecholamines norepinephrine and epinephrine throughout the sympathetic nervous system.[1][4][7] They comprise three alpha-1 (α1A, α1B, α1D), three alpha-2 (α2A, α2B, α2C), and three beta (β1, β2, β3) subtypes, which couple to different G proteins (Gq, Gi, or Gs) to regulate intracellular calcium and cyclic AMP signaling in a tissue- and subtype-specific manner.[6][7][8][9] Alpha-1 receptors primarily drive smooth muscle contraction and vasoconstriction, alpha-2 receptors inhibit neurotransmitter release and modulate vascular and metabolic tone, while beta-1 receptors predominate in the heart to increase rate and contractility and beta-2 receptors mediate bronchodilation and vascular smooth muscle relaxation; beta-3 receptors regulate lipolysis and thermogenesis in adipose tissue.[1][5][7][9] Because of their central role in cardiovascular, respiratory, and metabolic regulation, adrenergic receptors are major drug targets in hypertension, heart failure, ischemic heart disease, arrhythmias, shock, asthma and COPD, overactive bladder, and metabolic disorders.[1][3][7][9] Numerous therapeutics—including alpha agonists and antagonists, selective and nonselective beta-blockers, beta-2 bronchodilators, and beta-3 agonists—achieve their effects by modulating specific adrenergic receptor subtypes.[1][3][7][10] The same broad physiological influence also underlies important safety liabilities, such as hypotension, arrhythmias, bronchospasm, and metabolic disturbances, which necessitate careful selection of subtype, tissue selectivity, and dosing in drug development and clinical use.[1][7][9][10]

Other names

alpha-adrenergic receptorbeta-adrenergic receptoralpha-adrenoceptorbeta-adrenoceptoradrenoceptoradrenergic receptor (α and β)alpha- and beta-adrenoceptor

alpha-adrenergic receptor agonist; alpha-adrenergic receptor antagonist (alpha-blocker); beta-adrenergic receptor agonist; beta-adrenergic receptor antagonist (beta-blocker); nonselective alpha/beta-adrenergic receptor agonist; nonselective alpha/beta-adrenergic receptor antagonist; selective beta-1 adrenergic receptor antagonist; selective beta-2 adrenergic receptor agonist; selective beta-3 adrenergic receptor agonist; selective alpha-1 adrenergic receptor antagonist; selective alpha-2 adrenergic receptor agonist