alpha1

Alpha1 is a designation used across several domains, and it does not denote a single entity. It is a shorthand label that appears in different contexts to refer to distinct biological or chemical concepts.

In physiology and pharmacology, alpha-1 often refers to the alpha-1 adrenergic receptor family, a group of G protein-coupled receptors that respond to catecholamines such as norepinephrine. The main subtypes are alpha-1A, alpha-1B, and alpha-1D, encoded by the genes ADRA1A, ADRA1B, and ADRA1D. Activation signals through Gq/11 to activate phospholipase C, generating IP3 and DAG, and increasing intracellular calcium. This leads to smooth muscle contraction in vascular beds, the iris dilator muscle, the urinary tract, and other tissues. Clinically, alpha-1-adrenergic agonists (e.g., phenylephrine) raise blood pressure, while alpha-1 antagonists (e.g., doxazosin, terazosin, prazosin, and tamsulosin) are used to treat hypertension and benign prostatic hyperplasia. Adverse effects can include orthostatic hypotension and dizziness.

In biochemistry and medicine, Alpha-1 antitrypsin (A1AT) is a serine protease inhibitor encoded by the SERPINA1 gene. It is synthesized primarily in the liver and released into the bloodstream, where it protects lung tissue from neutrophil elastase during inflammation. Deficiency, most commonly the PiZZ genotype, predisposes to early-onset emphysema and liver disease. Diagnosis involves serum level testing and phenotypic/genotypic analysis, and management may include avoidance of lung irritants and, in some cases, augmentation therapy with purified A1AT.

The label alpha1 also appears in other gene and protein names as a prefix or subunit designation; usage is context dependent.