Erschienen in:
British Journal of Pharmacology, 158 (2009) 1, Seite 277-286
Sprache:
Englisch
DOI:
10.1111/j.1476-5381.2009.00224.x
ISSN:
0007-1188;
1476-5381
Entstehung:
Anmerkungen:
Beschreibung:
Background and purpose:Indacaterol is a novel β2‐adrenoceptor agonist in development for the treatment of chronic obstructive pulmonary disease. The aim of this study was to investigate the comparative pharmacology of indacaterol in recombinant cells expressing the common polymorphic variants of the human β2‐adrenoceptor and in human primary airway smooth muscle (ASM) cells.Experimental approach:Chinese hamster ovarian‐K1 cell lines expressing high and low levels of the common human β2‐adrenoceptor variants were generated [Gly16‐Glu27‐Val34‐Thr164(GEVT), RQVT, GQVT] and also the rare GQVI variant. Human primary ASM cells were isolated from explants of trachealis muscle. Adenosine‐3′,5′‐cyclic‐monophosphate production was used as an outcome measure.Key results:In both the low‐ and high‐expression recombinant GEVT ‘wild type’ cell lines indacaterol is a high‐efficacy agonist. Salmeterol and formoterol were identified as low‐ and high‐efficacy agonists, respectively, and showed similar potencies to indacaterol irrespective of the β2‐adrenoceptor genotype. The I164 variant cell line was associated with a reduced capacity to generate adenosine‐3′,5′‐cyclic‐monophosphate in response to β2‐adrenoceptor agonist. In the human primary ASM cells indacaterol gave a maximal response intermediate between that of salmeterol and formoterol.Conclusions and implications:These data demonstrate that indacaterol is a high‐efficacy agonist in recombinant cell systems but acts with lower efficacy in human primary ASM cells. No marked genotype‐dependent effects were observed for common variants; however, changes in I164 receptor activity were identified, which were dependent on the level of expression of β2‐adrenoceptors.