A subclass of beta-adrenergic receptors (receptors, adrenergic, beta). The adrenergic beta-2 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.