Table 2.
pEC50, α, pKapp and pKB values for histamine H3-receptor ligands in the guinea-pig ileum bioassay
| H3-receptor agonist | pEC50 (n) | α (n) | pKapp | H3-receptor antagonist | pA2 (n) |
|---|---|---|---|---|---|
| imetit | 7.95±0.04 (12) | 0.90±0.09 (12) | 7.61±0.16 | thioperamide | 8.53±0.08 (20) |
| proxyfan | 7.29±0.19 (4) | 0.35±0.07 (4) | 7.66±0.49 | iodophenpropit | 8.82±0.34 (4)c |
| 7.34±0.10 (4)a | |||||
| chloroproyfan | 7.85±0.14 (4) | 0.45±0.12 (4) | 8.04±0.25 | JB96132 | 8.58±0.10 (54) |
| bromoproxyfan | 8.27±0.10 (9) | 0.69±0.07 (9) | 7.76±0.33 | JB96134 | 6.96±0.10 (6)c |
| iodoproxyfan | 8.33±0.11 (10) | 0.90±0.05 (10) | 8.11±0.21 | JB97034 | 7.22±0.16 (5)c |
| R-α-MH | 7.64±0.06 (25) | 1.00±0.05 (25) | 7.19±0.20 (3)b | JB95130 | 5.44±0.26 (7)c |
| N-α-MH | 7.41±0.07 (5) | 0.93±0.10 (5) | 7.16e | GR175737 | 8.29±0.28 (4)c |
| S-α-MH | 6.52±0.03 (10) | 0.99±0.08 (10) | 5.59±0.14 | GT-2227 | 6.82±0.11 (70) |
| histamine | 7.40±0.04 (6) | 1.16±0.11 (6) | 6.37±0.16 | clobenpropit | 9.93±0.12 (3)d |
Abbreviations: N-α-MH, N-α-methylhistamine; R-α-MH, R-α-methylhistamine; S-α-MH, S-α-methylhistamine.
Data shown are the mean±s.e.m.; n=number of tissues used unless stated otherwise. The error on the pKapp values is the fitting error.
a
The pA2 of proxyfan determined in four separate experiments±s.e.m.
b
Mean pKapp from three separate experiments±s.e.m.
c
pA2 determined from a single antagonist concentration.
d
pA2 determined in three separate experiments.