Figure 4.

EC₅₀ for betaxolol-induced upregulation of CAM β₂-adrenoceptor-Renilla luciferase is similar to ligand K_i. (A) Cells of a clone of HEK293 cells stably expressing CAM β₂-adrenoceptor-Renilla luciferase were grown in a 96 well microtitre plate and exposed to various concentrations of betaxolol or propranolol for 24 h. Renilla luciferase activity was then monitored as described in Methods. (B) The capacity of various concentrations of betaxolol or propranolol to compete with [³H]-DHA (2 nM) to bind to CAM β₂-adrenoceptor-Renilla luciferase in membranes of the clone used in (A) was assessed. Data represent means±s.e.mean from three experiments.