Table 1. Functional agonist and antagonist potencies at primary h-CM cell B₂-receptor compared with h-TM cell responses, and ligand binding to human cloned B₂-receptors.

Compound	Agonist Potency at stimulating [Ca2+]i mobilization in primary h-CM cells (EC50, nM)	Agonist Potency at stimulating [Ca2+]i mobilization in primary h-TM cells (EC50, nM)	Ligand binding inhibition constant at human cloned B2 receptors (Ki, nM)
Agonists
Hyp3-BK	2.2±0.2	1	1.9±1.1
BK	2.4±0.2	1	0.5±0.01
Lys-BK	3.2±0.8	2	1.8±0.7
RMP-7	3.7±1.2	nd	11.3±1.1
Met-Lys-BK	16.1±6.1	7	73.0±24.7
Des-Arg9-BK	4,200±570	3,600	10,400±5,900
Antagonists blocking the actions of BK or competing for [3H]-BK binding to B2-receptor	Antagonist potency (IC50, nM)	Antagonist potency (IC50, nM)	Ligand binding inhibition constant at human cloned B2 receptors (Ki, nM)
HOE-140	1.4±0.1	5	0.5±0.2
(S)-WIN-64338	174±18	270	170.0±52.2

The [Ca²⁺]_i mobilization data in h-CM cells are mean ± SEM from 3 to 7 experiments. The [³H]-BK binding data are from up to 19 experiments. Preliminary h-TM cell data are shown for comparison purposes where the potency values have been rounded-off for clarity. The pharmacology of the h-CM and h-TM cell [Ca²⁺]_i mobilization data was well correlated: r=0.99, p<0.0001, n=7. Also, the human cloned B₂-receptor binding pharmacology and h-CM [Ca²⁺]_i mobilization data correlated well: r=0.99, p<0.0001, n=8; nd represents not determined.