Table 2.
pKD values for H3 antagonism
| Agonist | pKD values | |||||||||||
| Iodophen-propit | n | Cloben-propit | n | zolatidine | n | conessine | n | thioperamide | n | cimetidine | n | |
| histamine | 8.65 ± 0.07 | 19 | 9.42 ± 0.04 | 9 | 6.51 ± 0.07 | 19 | 8.29 ± 0.05 | 15 | 7.22 ± 0.04 | 23 | 5.64 ± 0.11 | 11 |
| N-α-methylhistamine | 8.59 ± 0.10 | 16 | 9.42 ± 0.06 | 15 | 6.46 ± 0.07 | 17 | 8.27 ± 0.04 | 12 | 7.37 ± 0.06 | 18 | 5.57 ± 0.08 | 9 |
| R-α-methylhistamine | 8.57 ± 0.09 | 15 | 9.21 ± 0.08 | 15 | 6.52 ± 0.06 | 14 | 8.24 ± 0.06 | 9 | 7.33 ± 0.04 | 17 | 5.62 ± 0.12 | 8 |
| S-α-methylhistamine | 8.72 ± 0.05 | 14 | 9.25 ± 0.05 | 13 | 6.54 ± 0.07 | 18 | 8.28 ± 0.05 | 12 | 7.20 ± 0.05 | 17 | 5.64 ± 0.06 | 9 |
| imetit | 8.78 ± 0.06 | 16 | 9.20 ± 0.05 | 12 | 6.62 ± 0.08 | 17 | 8.24 ± 0.10 | 12 | 7.29 ± 0.06 | 13 | 5.64 ± 0.08 | 10 |
| immepip | 8.66 ± 0.07 | 14 | 9.36 ± 0.04 | 12 | 6.55 ± 0.07 | 17 | 8.09 ± 0.07 | 12 | 7.22 ± 0.09 | 15 | 5.70 ± 0.09 | 9 |
| immethridine | 8.81 ± 0.08 | 12 | 9.21 ± 0.06 | 12 | 6.66 ± 0.05 | 12 | 8.42 ± 0.10 | 11 | 7.31 ± 0.06 | 12 | 5.72 ± 0.09 | 4 |
| proxyfan | 8.82 ± 0.05 | 7 | 9.25 ± 0.08 | 7 | 6.78 ± 0.06 | 9 | 8.56 ± 0.08 | 5 | 7.59 ± 0.03 | 9 | 5.61 ± 0.11 | 6 |
| VUF 8430 | 8.53 ± 0.08 | 6 | 9.11 ± 0.19 | 4 | 6.38 ± 0.10 | 4 | 8.15 ± 0.08 | 4 | 7.15 ± 0.27 | 4 | 5.53 ± 0.13 | 4 |
| impentamine | 8.60 ± 0.09 | 6 | 9.01 ± 0.10 | 4 | 6.52 ± 0.10 | 4 | 8.38 ± 0.11 | 4 | 7.47 ± 0.10 | 5 | 5.70 ± 0.01 | 5 |
| agonist | Log KD values | |||||||||||
| Dimethin-dine | n | Chlorpheni-ramine | n | VUF 5681 | n | ranitidine | n | triprolidine | n | clemastine | n | |
| histamine | 5.63 ± 0.07 | 7 | 5.32 ± 0.06 | 8 | 7.77 ± 0.08 | 5 | 5.05 ± 0.08 | 9 | 5.35 ± 0.05 | 7 | 5.73 ± 0.08 | 10 |
| N-α-methylhistamine | 5.67 ± 0.17 | 6 | 5.51 ± 0.07 | 3 | 7.95 ± 0.14 | 4 | 5.05 ± 0.08 | 9 | 5.34 ± 0.08 | 6 | 5.69 ± 0.13 | 7 |
| R-α-methylhistamine | 5.65 ± 0.04 | 5 | 5.44 ± 0.04 | 4 | 7.60 ± 0.07 | 4 | 5.18 ± 0.06 | 7 | 5.58 ± 0.05 | 5 | 5.79 ± 0.09 | 7 |
| S-α-methylhistamine | 5.67 ± 0.03 | 4 | 5.44 ± 0.08 | 3 | 7.75 ± 0.04 | 4 | 4.95 ± 0.10 | 7 | 5.47 ± 0.08 | 6 | 5.74 ± 0.11 | 8 |
| imetit | 5.60 ± 0.16 | 8 | 5.58 ± 0.08 | 4 | 7.85 ± 0.08 | 4 | 4.96 ± 0.09 | 7 | 5.43 ± 0.09 | 7 | 5.69 ± 0.15 | 6 |
| immepip | 5.72 ± 0.16 | 5 | 5.59 ± 0.12 | 4 | 7.72 ± 0.10 | 3 | 5.12 ± 0.06 | 6 | 5.61 ± 0.13 | 4 | 5.79 ± 0.15 | 6 |
| immethridine | 5.38 ± 0.05 | 9 | 5.53 ± 0.05 | 4 | 7.79 ± 0.12 | 4 | 5.19 ± 0.09 | 3 | 5.53 ± 0.13 | 3 | 5.50 ± 0.10 | 3 |
| proxyfan | 5.24 ± 0.14 | 3 | 5.39 ± 0.11 | 5 | 7.80 ± 0.03 | 3 | 4.97 ± 0.12 | 5 | 5.23 ± 0.07 | 5 | 5.60 ± 0.11 | 6 |
| VUF 8430 | 5.11 ± 0.09 | 3 | 5.13 ± 0.15 | 4 | 7.71 ± 0.16 | 3 | 4.72 ± 0.01 | 3 | 5.26 ± 0.10 | 3 | 5.26 ± 0.06 | 4 |
| impentamine | 5.59 ± 0.24 | 3 | 5.21 ± 0.22 | 4 | * | 5.10 ± 0.09 | 5 | 5.65 ± 0.15 | 4 | 5.73 ± 0.09 | 5 | |
pKD values for 12 antagonists as determined from measurements of CRE-SPAP production from CHO-H3-cells made in the presence of the 12 different agonists. Values represent mean ± s.e.mean of n separate experiments. The pKD values quoted are for antagonism of the first component of the impentamine response.
* it was not possible to determine a pKD value for VUF 5681 in the presence of impentamine due to the partial agonist nature of both responses.