The β-adrenergic receptor (βAR) belongs to the superfamily of G-protein coupled receptors (GPCRs).  β-Adrenergic receptor stimulation by the sympathetic nervous system or circulating catecholamines is involved in peripheral blood circulation, metabolic regulation, muscle contraction, and central neural activities.  In the heart, acute βAR stimulation serves as the most powerful means to regulate cardiac output in response to a fight-or-flight situation.

There are three βAR subtypes in cardiac myocytes; β1AR, β2AR and β3AR¹. The receptors consist of seven membrane-spanning domains, three intra- and three extracellular loops, an extracellular N-terminal domain, and an intracellular C-terminal tail².