The β-arrestin-biased β-adrenergic receptor blocker carvedilol enhances skeletal muscle contractility

A decrease in skeletal muscle strength and functional exercise capacity due to aging, frailty, and muscle wasting poses major unmet clinical needs. These conditions are associated with numerous adverse clinical outcomes including falls, fractures, and increased hospitalization. Clenbuterol, a beta(2)-adrenergic receptor (beta(2)AR) agonist enhances skeletal muscle strength and hypertrophy; however, its clinical utility is limited by side effects such as cardiac arrhythmias mediated by G protein signaling. We recently reported that clenbuterol-induced increases in contractility and skeletal muscle hypertrophy were lost in beta-arrestin 1 knockout mice, implying that arrestins, multifunctional adapter and signaling proteins, play a vital role in mediating the skeletal muscle effects of beta(2)AR agonists. Carvedilol, classically defined as a beta AR antagonist, is widely used for the treatment of chronic systolic heart failure and hypertension, and has been demonstrated to function as a beta-arrestin-biased ligand for the beta(2)AR, stimulating beta-arrestin-dependent but not G protein-dependent signaling. In this study, we investigated whether treatment with carvedilol could enhance skeletal muscle strength via beta-arrestin-dependent pathways. In a murine model, we demonstrate chronic treatment with carvedilol, but not other beta-blockers, indeed enhances contractile force in skeletal muscle and this is mediated by beta-arrestin 1. Interestingly, carvedilol enhanced skeletal muscle contractility despite a lack of effect on skeletal muscle hypertrophy. Our findings suggest a potential unique clinical role of carvedilol to stimulate skeletal muscle contractility while avoiding the adverse effects with beta AR agonists. This distinctive signaling profile could present an innovative approach to treating sarcopenia, frailty, and secondary muscle wasting.