title: Beta-Adrenergic Agonists.
abstract: Inhaled β₂-adrenoceptor (β₂-AR) agonists are considered essential bronchodilator drugs in the treatment of bronchial asthma, both as symptoms-relievers and, in combination with inhaled corticosteroids, as disease-controllers. In this article, we first review the basic mechanisms by which the β₂-adrenergic system contributes to the control of airway smooth muscle tone. Then, we go on describing the structural characteristics of β₂-AR and the molecular basis of G-protein-coupled receptor signaling and mechanisms of its desensitization/ dysfunction. In particular, phosphorylation mediated by protein kinase A and β-adrenergic receptor kinase are examined in detail. Finally, we discuss the pivotal role of inhaled β₂-AR agonists in the treatment of asthma and the concerns about their safety that have been recently raised.
authors.affiliation: Preventive and Occupational Medicine Unit, Respiratory Pathophysiology Laboratory, University Hospital San Martino, Largo R. Benzi, 10 - 16132 Genoa, Italy. giovanni.barisione@hsanmartino.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Barisione
authors.affiliation: Respiratory Pathophysiology Unit, Department of Internal Medicine, University of Genoa, Viale Benedetto XV - 16132 Genoa, Italy. michele.baroffio@unige.it.
authors.forename: Michele
authors.initials: M
authors.lastname: Baroffio
authors.affiliation: Respiratory Pathophysiology Unit, Department of Internal Medicine, University of Genoa, Viale Benedetto XV - 16132 Genoa, Italy. emanuele.crimi@unige.it.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Crimi
authors.affiliation: Respiratory Pathophysiology Unit, Department of Internal Medicine, University of Genoa, Viale Benedetto XV - 16132 Genoa, Italy. vito.brusasco@unige.it.
authors.forename: Vito
authors.initials: V
authors.lastname: Brusasco
keywords: G-protein-coupled receptor signaling; airway smooth muscle; bronchodilation; desensitization; safety issues; β2-adrenoceptors