Adrenergic beta2-Agonists

The beta-2 adrenoceptor couples to Gs (and to Gi) and binds adrenaline with roughly thirty times the affinity it has for noradrenaline, which is why it responds mainly to circulating adrenaline rather than to sympathetic nerve traffic. Drugs in this class activate it, raising cAMP in smooth muscle and relaxing it - the basis of bronchodilation and of uterine relaxation. A drug belongs here because it stimulates the beta-2 subtype rather than the beta-1 subtype.