Potencies of H1R antagonists in the GTPase assay in Sf9 membranes expressing hH1R, gpH1R and hH1R-F153L/I433V
Steady-state GTPase activity in Sf9 membranes expressing H1R constructs (+RGS4 or GAIP) was determined as described under Materials and Methods. Reaction mixtures contained 1 μM histamine and H1R antagonists at concentrations from 1 nM to 100 μM as appropriate to generate saturated concentration/response curves. Data were analyzed by nonlinear regression and were best fit to sigmoid concentration/response curves. Typical GTPase activities in the presence of 1 μM histamine between 2.5 to 3.0 pmol/mg/min. Data shown are the means ± S.D. of three to five experiments performed in duplicates each. We also calculated the ratio of the KB values for hH1R and gpH1R (Pot. Rat. gpH1R/hH1R) and the ratio of the KB values for hH1R and hH1R-F153L/I433V (Pot. Rat. M./hH1R).
Cpd. | Antagonist | KB hH1R | KB gpH1R | Pot. Rat. gpH1R/hH1R | hH1R-F153L/I433V | Pot. Rat. M./hH1R | |
|---|---|---|---|---|---|---|---|
| nM | |||||||
| 24 | Promazine | 1.08 ± 0.11 | 1.30 ± 0.19 | 0.83 | N.D. | N.D. | |
| 25 | Chlorpromazine | 2.55 ± 0.54 | 2.85 ± 1.34 | 0.89 | N.D. | N.D. | |
| 26 | Mianserin | 2.13 ± 1.17 | 3.16 ± 1.88 | 0.67 | N.D. | N.D. | |
| 27 | Cyproheptadine | 1.92 ± 0.13 | 2.64 ± 0.94 | 0.73 | N.D. | N.D. | |
| 28 | Diphenhydramine | 15.5 ± 1.77 | 16.4 ± 1.99 | 0.95 | N.D. | N.D. | |
| (R)-29 | (R)-(-)-Dimethindene | 2.68 ± 1.52 | 2.97 ± 1.49 | 0.90 | N.D. | N.D. | |
| (S)-29 | (S)-(+)-Dimethindene | 113.2 ± 30.9 | 94.5 ± 38.8 | 1.20 | N.D. | N.D. | |
| 30 | Mepyramine | 5.67 ± 0.88 | 2.30 ± 0.52* | 2.47 | 5.76 ± 1.10 | 0.99 | |
| 31 | Triprolidine | 4.37 ± 1.61 | 1.73 ± 0.32* | 2.52 | N.D. | N.D. | |
| 32 | (+)-Chlorpheniramine | 9.85 ± 2.32 | 4.97 ± 1.37* | 1.98 | N.D. | N.D. | |
| 33 | BU-E 42 | 554 ± 36.8 | 98.6 ± 19.7* | 5.62 | 698 ± 31.8* | 0.80 | |
| 34 | BU-E 43 | 332 ± 74.0 | 142 ± 37.7* | 2.34 | N.D. | N.D. | |
| 35 | Arpromidine | 332 ± 89.6 | 48.9 ± 12.9* | 6.79 | 465 ± 88.3 | 0.72 | |
| 36 | BU-E 47 | 724 ± 180 | 80.0 ± 16.8* | 9.05 | 477 ± 61.0* | 1.51 | |
| 37 | BU-E 48 | 543 ± 198 | 116 ± 31.0* | 4.68 | 528 ± 29.7 | 1.03 | |
| 38 | BU-E 75 | 499 ± 122 | 131 ± 10.4* | 3.81 | 1180 ± 64* | 0.42 | |
| 39 | D281 | 562 ± 123 | 352 ± 79 | 1.60 | N.D. | N.D. | |
| 40 | N-{2-[2-(3-Trifluoromethylphenyl)-1H-imidazol-4-yl]ethyl}pipe ridine | 1570 ± 148 | 454 ± 155* | 3.46 | 2310 ± 210* | 0.68 | |
| 41 | Terfenadine | 28.1 ± 4.97 | 38.5 ± 6.08 | 0.73 | N.D. | N.D. | |
| 42 | Fexofenadine | 226 ± 50.2 | 258 ± 61.0 | 0.88 | N.D. | N.D. | |
| 43 | Astemizole | 10.4 ± 1.42 | 12.7 ± 3.25 | 0.82 | N.D. | N.D. | |
| 44 | Azelastine | 1.71 ± 0.16 | 1.89 ± 0.17 | 0.90 | N.D. | N.D. | |
|
45
| Ketotifen | 0.96 ± 0.03 | 1.09 ± 0.30 | 0.88 | N.D. | N.D. | |
N.D., not determined; Cpd., compound.
↵ * P < 0.05 for comparison of hH1R versus other H1R constructs