The promise of beta3-adrenoceptor agonists to treat the overactive bladder.

The detrusor muscle contains beta-adrenoceptors (beta-ARs), of which two subtypes--beta1-AR and beta2-AR--have been identified in most species. Although beta2-AR has an important role in muscle relaxation, evidence suggests that a third subtype--beta3-AR--mediates relaxation of human detrusor muscle. This article reviews the evidence for beta3-AR in human detrusor muscle and urothelium and discusses the potential use of beta3-AR agonists for the treatment of overactive bladder. In addition, the cAMP-dependent and -independent mechanisms of relaxation by way of beta-ARs in rat detrusor muscle, with and without pre-contraction, are reported. Finally, the consequences of mutation of a beta3-AR gene (relating to the pathophysiology of idiopathic detrusor instability) are discussed.