β2-adrenoceptor polymorphisms:: Relation between in vitro and in vivo phenotypes

Beta(2)-adrenoceptors are expressed in many cell types throughout the body and play a pivotal role in the regulation of the cardiac, pulmonary, vascular, endocrine and central nervous system. Recent studies have discovered that beta(2)-adrenoceptor are polymorphic. Three common polymorphisms appear to influence receptor function: Arg16Gly, Gln27Glu, and Thr164Ile. In vitro studies of agonist-stimulation have shown that the Gly16 beta(2)-adrenoceptors demonstrate enhanced agonist-promoted down-regulation, while Glu27 variants seem to be resistant. The Ilel64 variant, on the other hand, demonstrates decreased responsiveness to agonist stimulation in vitro. However, the functional relevance and phenotypic consequence of such beta(2)-adrenoceptor variants in vivo is still unclear. The aim of this review is therefore to provide an overview about the somewhat controversy in vitro, ex vivo and in vivo studies. (C) 2004 Elsevier Inc. All rights reserved.