beta-1 adrenergic receptors (adrenoceptors), member of the class A family of seven-transmembrane G protein-coupled receptors
The beta-1 adrenergic receptor (beta-1 adrenoceptor), also known as beta-1 AR, is activated by adrenaline (epinephrine) and plays important roles in regulating cardiac function and heart rate. The human heart contains three subtypes of the beta AR: beta-1 AR, beta-2 AR, and beta-3 AR. Beta-1 AR and beta-2 AR, which expressed at about a ratio of 70:30, are the major subtypes involved in modulating cardiac contractility and heart rate by positively stimulating the G(s) protein-adenylate cyclase-cAMP-PKA signaling pathway. In contrast, beta-3 AR produces negative inotropic effects by activating inhibitory G(i) proteins. The aberrant expression of beta-ARs can lead to cardiac dysfunction such as arrhythmias or heart failure.