ADRB2 and heart failure: [4]–[6]ADRβ2+46*G (Gly16) results in increased agonist-stimulated receptor down-regulation while ADRβ2+79*G (Glu27) is highly resistant.[7]ADRβ2+491*T (Ile164) alters receptor binding affinity with reduced activation in vitro[8] and blunted in vivo responses to terbutaline in healthy and cardiac failure subjects. [9], [10]