Alpha-1 and beta-1 adrenergic receptors (Alpha1/Beta1-AR)

Alpha-1 and beta-1 adrenergic receptors are distinct classes of G protein-coupled receptors (GPCRs) that collectively regulate the sympathetic nervous system's response to catecholamines like norepinephrine and epinephrine [3, 7]. Alpha-1 receptors (comprising α1A, α1B, and α1D subtypes) primarily signal through the Gq pathway to increase intracellular calcium, leading to smooth muscle contraction and systemic vasoconstriction [1, 6]. In contrast, beta-1 receptors primarily signal through the Gs pathway to increase cyclic AMP (cAMP), which enhances cardiac contractility and heart rate while also stimulating renin release from the kidneys [5, 6]. These receptors are major therapeutic targets in the treatment of cardiovascular disorders, including hypertension and heart failure [1, 10]. Drugs that interact with both receptor types, such as the mixed antagonist carvedilol, are used to reduce peripheral resistance and protect the heart from chronic sympathetic overstimulation [6, 10]. Conversely, mixed agonists like norepinephrine are vital in emergency medicine for treating life-threatening hypotension and shock [3, 6].

Other names

Alpha-1/beta-1 adrenoceptorsADRA1/ADRB1Mixed alpha/beta adrenergic receptorsAlpha1- and beta1-adrenoceptors

Agonists activate Gq-coupled Alpha-1 receptors to increase intracellular calcium and Gs-coupled Beta-1 receptors to increase cAMP, leading to vasoconstriction and increased cardiac output [3, 5, 6]. Antagonists block these receptors to lower blood pressure and reduce cardiac demand [8, 10].