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

The alpha-1A and alpha-1B adrenergic receptors are members of the G protein-coupled receptor (GPCR) superfamily that mediate the effects of the endogenous catecholamines, epinephrine and norepinephrine (UniProt, 2024). The alpha-1A subtype is predominantly expressed in the prostate, bladder neck, and urethral smooth muscle, where its activation leads to contraction and resistance to urine flow (StatPearls, 2023). In contrast, the alpha-1B subtype is the major isoform found in vascular smooth muscle, playing a critical role in regulating peripheral vascular resistance and systemic blood pressure (PubMed, 2022). These receptors are primary therapeutic targets for conditions such as benign prostatic hyperplasia (BPH) and hypertension (NIH, 2023). Selective alpha-1A antagonists, like tamsulosin and silodosin, are used to improve urinary symptoms in BPH by relaxing prostatic smooth muscle with minimal impact on blood pressure (PubChem, 2024). Conversely, non-selective alpha-1 blockers like prazosin and doxazosin are utilized for their antihypertensive effects. Understanding the distribution and signaling of these subtypes is essential for developing drugs that balance efficacy in urological or cardiovascular conditions while minimizing side effects like orthostatic hypotension (StatPearls, 2023).

Other names

Alpha-1A adrenoceptorAlpha-1B adrenoceptorADRA1AADRA1BAlpha-1A/B adrenergic receptor

Antagonism of alpha-1 adrenergic receptors leads to the relaxation of smooth muscle in the prostate and blood vessels, while agonism induces contraction and vasoconstriction.