Beta-2 adrenergic receptor
In medicine and physiology, beta-2 adrenergic receptors, or β-2 adrenergic receptors, are cell surface receptors of the G-protein-coupled receptor type that are in the sympathetic nervous system. Beta-2 adrenergic receptors are a "subclass of beta-adrenergic receptors (receptors, adrenergic, beta). Beta-2 Adrenergic receptors are more sensitive to epinephrine than to norepinephrine and have a high affinity for the agonist terbutaline. They are widespread, with clinically important roles in skeletal muscle, liver, and vascular, bronchial, gastrointestinal, and genitourinary smooth muscle." Their functions include vasodilation.
Adrenergic beta-agonists, such as terbutaline, are used to treat asthma by preventing bronchoconstriction. Adrenergic beta-antagonists, such as atenolol or metoprolol are used to treat cardiac diseases.