Affinity of various H3 agonists and antagonists for the different rat H3 receptor isoforms as determined by [125I]IPP binding studies. Data are the means ± S.E.M. from at least three independent experiments
| Receptor subtype | [125I]IPP | pKiValues | ||||||
|---|---|---|---|---|---|---|---|---|
| KD | Bmax | Histamine | Immepip | (R)-α-methyl histamine | Impentamine | Clobenpropit | Thioperamide | |
| nM | pmol/mg of protein | |||||||
| H3A | 2.1 ± 0.2 | 1.2 ± 0.07 | 5.7 ± 0.15 | 7.5 ± 0.08 | 6.4 ± 0.2 | 6.9 ± 0.06 | 8.3 ± 0.02 | 7.2 ± 0.08 |
| H3B | 1.4 ± 0.1 | 1.2 ± 0.09 | 6.2 ± 0.1 | 8.0 ± 0.06 | 6.9 ± 0.08 | 7.4 ± 0.05 | 8.6 ± 0.1 | 7.5 ± 0.15 |
| H3C | 1.3 ± 0.1 | 1.3 ± 0.1 | 6.3 ± 0.07 | 8.0 ± 0.1 | 7.1 ± 0.14 | 7.6 ± 0.04 | 8.5 ± 0.03 | 7.6 ± 0.06 |