Table 3.
pKI and nH values for histamine H3-receptor agonists and antagonists at 4, 12, 21 and 30°C (277, 285, 294 and 300 K)
| Ligand | Temperature (K) |
Buffer A |
Buffer ACa |
||||
|---|---|---|---|---|---|---|---|
| pKI or pKI′ | nH | n | pKI or pKI′ | nH | n | ||
| Histamine H3-receptor agonists | |||||||
| proxyfan | 303 | 8.51±0.13 | 0.97±0.21 | 3 | ND | ND | |
| 294 | 8.61±0.17 | 0.73±0.06 | ND | ND | |||
| 285 | 8.05±0.08 | 0.89±0.06 | ND | ND | |||
| 277 | 7.89±0.07 | 1.07±0.12 | ND | ND | |||
| chloroproxyfan | 303 | 9.04±0.15 | 0.81±0.04a | 5 | ND | ND | 4 |
| 294 | 9.00±0.22 | 0.77±0.04a | 7.76±0.12 | 1.04±0.05 | |||
| 285 | 8.78±0.14 | 0.71±0.07a | 7.68±0.14 | 0.88±0.04 | |||
| 277 | 8.66±0.10 | 0.90±0.12 | 7.82±0.20 | 0.94±0.07 | |||
| bromoproxyfan | 303 | 9.32±0.05 | 0.77±0.07a | 3 | ND | ND | 4 |
| 294 | 9.28±0.02 | 0.83±0.09 | 8.13±0.26 | 0.99±0.04 | |||
| 285 | 9.04±0.14 | 0.81±0.04a | 8.04±0.30 | 0.91±0.06 | |||
| 277 | 9.13±0.15 | 0.88±0.16 | 8.16±0.29 | 0.95±0.08 | |||
| iodoproxyfan | 303 | 9.82±0.07 | 0.65±0.10a | 4 | ND | ND | 4 |
| 294 | 9.79±0.05 | 0.67±0.03a | 8.10±0.36 | 0.94±0.08 | |||
| 285 | 9.45±0.10 | 0.62±0.08a | 8.26±0.26 | 0.88±0.02 | |||
| 277 | 9.27±0.08 | 0.94±0.16 | 8.31±0.31 | 0.91±0.03 | |||
| imetit | 303 | 9.17±0.19 | 0.76±0.09 | 4 | ND | ND | 6 |
| 294 | 9.33±0.12 | 0.80±0.12 | 7.93±0.17 | 0.86±0.05 | |||
| 285 | 9.03±0.07 | 0.85±0.08 | 7.87±0.12 | 0.89±0.05 | |||
| 277 | 9.16±0.12 | 0.87±0.08 | 7.89±0.14 | 0.94±0.07 | |||
| R-α-MH | 303 | 9.13±0.22 | 0.63±0.06a | 5 | ND | ND | 5 |
| 294 | 9.15±0.18 | 0.63±0.02a | 7.30±0.14 | 0.83±0.07 | |||
| 285 | 8.89±0.21 | 0.66±0.05a | 7.09±0.20 | 0.81±0.05a | |||
| 277 | 8.87±0.22 | 0.62±0.03a | 7.21±0.22 | 0.86±0.04 | |||
| immepip | 303 | 9.47±0.03 | 0.71±0.06a | 5 | ND | ND | 5 |
| 294 | 9.53±0.04 | 0.88±0.05 | 8.07±0.11 | 0.86±0.05 | |||
| 285 | 9.39±0.13 | 0.82±0.05a | 7.91±0.12 | 0.91±0.03a | |||
| 277 | 9.34±0.14 | 0.73±0.03a | 7.99±0.19 | 0.90±0.02a | |||
| Histamine H3-receptor antagonists | |||||||
| JB96132 | 303 | 8.95±0.07 | 1.08±0.14 | 3 | ND | ND | 4 |
| 294 | 9.17±0.13 | 0.99±0.06 | 8.97±0.14 | 1.06±0.12 | |||
| 285 | 9.11±0.09 | 0.85±0.05 | 8.82±0.17 | 0.95±0.04 | |||
| 277 | 9.49±0.05 | 0.97±0.09 | 9.20±0.24 | 0.94±0.03 | |||
| thioperamide | 303 | 8.35±0.06 | 0.90±0.08 | 6 | ND | ND | 5 |
| 294 | 8.50±0.05 | 0.82±0.04a | 9.00±0.15 | 0.96±0.11 | |||
| 285 | 8.66±0.09 | 0.96±0.06 | 8.84±0.12 | 0.88±0.05 | |||
| 277 | 8.75±0.02 | 0.81±0.04a | 9.00±0.13 | 0.86±0.03a | |||
Abbreviation: ND, not determined.
Data are the mean±s.e.m. pKI′ is the ligand affinity when nH is significantly less than unity.
a
nH significantly different from unity, P<0.05 t-test.