H4 receptor expression and agonist efficacy and potency in cell- ines expressing different levels of the H4 receptor
[3H]Histamine binding was used to determine the level of H4 receptor expression in a number of U2OS-H4 cell lines. These cell lines were then used to characterize the efficacy and potency of histamine and JNJ7777120. Efficacy of each agonist is expressed as a percentage of the maximal response to that ligand observed in the highest expressing clone (ER1J). In addition, the percentage efficacy for JNJ7777120 compared with the histamine response in that clone is shown in parentheses. Data are shown as means ± S.E.M. for three independent experiments.
| [3H]-histamine | Histamine | JNJ7777120 | ||||
|---|---|---|---|---|---|---|
| Bmax | Kd | pEC50 | Efficacy | pEC50 | Efficacy | |
| pmol/mg | nM | % | % | |||
| U2OS-H4_ER1J | 2.2 ± 0.2 | 10.5 ± 2.3 | 7.5 ± 0.07 | 75.7 | 7.9 ± 0.10 | 100 (66.0) |
| U2OS-H4_ER1L | 1.3 ± 0.1 | 11.6 ± 3.7 | 7.7 ± 0.10 | 42.9 | 8.1 ± 0.10 | 57.2 (75.9) |
| U2OS-H4_ER1B | 1.1 ± 0.2 | 10.8 ± 3.4 | 7.5 ± 0.05 | 27.8 | 8.0 ± 0.05 | 37.2 (64.8) |
| U2OS-H4_ER1K | 0.3 ± 0.1 | 22.2 ± 13.0 | 7.7 ± 0.08 | 3.1 | 7.9 ± 0.26 | 4.2 (97.0) |