β-Adrenoceptor regulation and functional responses in the guinea-pig following chronic administration of the long-acting β2-adrenoceptor agonist formoterol

Abstract

Formoterol is a long acting β2-adrenoceptor agonist designed for the alleviation of the symptoms of asthma. This study examined the effects of 14 day administration of formoterol (200 μg/kg/day i.p.) on β1- and β2-adrenoceptors in guinea-pig cardiac and lung tissue. Quantitative autoradiography was used to measure changes in receptor density and organ bath studies determined alterations in functional response. Formoterol treatment produced marked reductions of between 43% and 77% in β2-adrenoceptor density in all regions of the heart (atrioventricular node, bundle of His, right and left bundle branches, interventricular and interatrial septa, right and left atria, ventricles and apex) and lu..