Table 2

Binding parameters of ¹²⁵I-cyanopindolol, [³H]propranolol, and [³H]ICI 118551 derived from saturation experiments carried out in membranes expressing the β₂AR alone or in combination with Gαsβ1γ2

Ligand	n	K_d		B_max
Ligand	n	β₂AR	β₂AR/αsβ1γ2	β₂AR	β₂AR/αsβ1γ2
				pmol/mg protein
Cyanopindolol	4	94 ± 19 pM	84 ± 23 pM	18 ± 2.15	11 ± 0.39^2-a
Propranolol	3	0.9 ± 0.31 nM	0.7 ± 0.26 nM	14 ± 0.56	8.6 ± 1.00^2-b
ICI 118551	4	1.3 ± 0.17 nM	1.3 ± 0.37 nM	17 ± 1.78	8.4 ± 1.40^2-b

K _d and B _max were determined as described under Materials and Methods. Data were analyzed using the curve-fitting software GraphPad-Prism. Values represent means ± S.E.M. of n independent experiments performed in triplicates.

↵2-a p < 0.05.
↵2-b p < 0.01.