Table 7. Agonist Responses of Second- and Third-Generation Ligands at the Human β₁-, β₂-, and β₃-Adrenoceptors^a.

	β1			β2			β3
compd	log EC50 β1	% isop max	n	β2b	% isop max at 10 μM	n	β3b	% isop max at 10 μM	n
1	–8.64 ± 0.04	37.1 ± 2.2	5	10 μM	15.2 ± 0.7	4	10 μM	8.6 ± 0.4	4
19	–8.01 ± 0.04	33.6 ± 2.4	6	10 μM	8.0 ± 1.1	7	10 μM	12.5 ± 2.3	7
29a	–8.44 ± 0.04	25.5 ± 1.1	5	10 μM	15.3 ± 1.1	4	10 μM	4.0 ± 0.6	3
29b	–8.64 ± 0.04	23.8 ± 1.5	5	10 μM	16.0 ± 1.3	4	10 μM	7.9 ± 0.1	4
29c	–7.64 ± 0.04	35.9 ± 1.7	5	10 μM	27.8 ± 2.3	3	10 μM	1.3 ± 0.1	3
37a	–8.35 ± 0.10	28.3 ± 1.9	5	10 μM	15.3 ± 1.0	4	10 μM	4.0 ± 0.3	4
37l	–8.52 ± 0.08	29.1 ± 1.7	4	10 μM	12.7 ± 0.7	3	10 μM	2.0 ± 0.1	3

^aValues represent the mean ± SEM of n separate experiments. Log EC₅₀ values and % isoprenaline maximal responses were obtained from ³H-cAMP accumulation for cells expressing the human β₁-adrenoceptor.

^bFor the human β₂- and β₃-adrenoceptors, the top of the agonist concentration response curve was not obtained even with the maximum concentration of ligand. In these instances, the percentage of isoprenaline response is given for the response at 10 μM of ligand.