Alpha-1A and Alpha-1B adrenergic receptors (ADRA1A/ADRA1B)

The Alpha-1A and Alpha-1B adrenergic receptors (ADRA1A and ADRA1B) are G protein-coupled receptors (GPCRs) that mediate the effects of the sympathetic nervous system by binding norepinephrine and epinephrine [1, 3]. These receptors primarily signal through the Gq/11 pathway, activating phospholipase C and increasing intracellular calcium to trigger smooth muscle contraction [5, 6]. The Alpha-1A subtype is highly expressed in the prostate, bladder neck, and certain vascular beds, where it regulates urinary flow and vascular tone [1, 10]. In contrast, the Alpha-1B subtype is more prevalent in the heart and systemic vasculature, contributing to the regulation of blood pressure and cardiac growth [2, 13]. Clinically, these receptors are critical targets for treating benign prostatic hyperplasia (BPH) and hypertension [4, 10]. Alpha-1A selective antagonists, such as tamsulosin and silodosin, are used to relax prostatic smooth muscle and improve urinary symptoms with minimal impact on blood pressure [1, 5]. Non-selective antagonists like doxazosin and prazosin block both subtypes to treat hypertension by inducing vasodilation [1, 10]. However, therapeutic use is often limited by safety concerns such as orthostatic hypotension and dizziness [1, 10]. Ongoing research also investigates the potential of Alpha-1A agonists in heart failure and neuroprotection, highlighting the diverse roles of these receptor subtypes in human physiology [3, 13].

Other names

Alpha-1A adrenoceptorAlpha-1B adrenoceptorADRA1AADRA1BAlpha-1A adrenoreceptorAlpha-1B adrenoreceptorα1A-ARα1B-AR

Alpha-1 adrenergic receptor antagonism; Alpha-1 adrenergic receptor agonism