Table 1

Values and coupling efficiencies of agonists in BEAS-2B cells

Agonist	K_d	EC₅₀	C/E	Percentage of Epinephrine
	nM
10 μM Epinephrine	298 (±38)	51	0.173	100
2 μM Fenoterol	145 (±27)	36	0.108	62.4
6 μM Albuterol	143 (±7)	103	0.014	8.1
15 μM Dobutamine	891 (±3)		0.004^*	2.3
100 μM Ephedrine	2591 (±517)		0.002^*	1.2

K _d values (range of two determinations shown in parentheses) were obtained as described under Experimental Procedures. Coupling efficiencies were determined using the formula CE = (K _d − EC₅₀)/EC₅₀ r, where r represents receptor number. EC₅₀ values for dobutamine and ephedrine could not be reliably determined in the BEAS-2B cells, so coupling efficiencies for these agonists (denoted by ∗) are reprinted with permission from January et al. (1997). Coupling efficiency values for the agonists were calculated as percentage of coupling efficiency of epinephrine to establish an approximate relative measure of agonist strength.