Pharmacological characterization of the anti-α1 and -α5 immunoprecipitated GABAA receptors from rat hippocampus
| Antibody | nH | Ki | ||
|---|---|---|---|---|
| Type I | Type II | |||
| nM | nM | |||
| C1218.872 | ||||
| Anti-α1 | 0.74 ± 0.01 | 47.5 ± 5.2 | 0.7 ± 0.06 | |
| (62.5 ± 2.2) | (38.1 ± 2.3) | |||
| Anti-α5 | 1.05 ± 0.07 | N.D. | 0.81 ± 0.15 | |
| (100) | ||||
| Type IIM | Type IIL | |||
| nM | nM | |||
| Zolpidem | ||||
| Anti-α1 | 0.53 ± 0.03 | 25.0 ± 7.0 | 415.0 ± 200.0 | 9.3 ± 3.0 |
| (78.5 ± 3.0) | (11.5 ± 9.1) | (11.4 ± 2.0) | ||
| Anti-α5 | 0.90 ± 0.05 | N.D. | N.D. | 5.0 ± 3.0 |
| (100) | ||||
Solubilized receptor was immunoadsorbed to the different IgG-protein A-Sepharose columns, washed extensively, and aliquots of anti-α1 or -α5 immunobeads (0.4–0.6 pmol of [3H]FMZ binding activity/tube) were used. Displacement experiments were performed by determining binding activity of 1.2 nM [3H]FMZ and 13 or 10 different concentrations of zolpidem (ranging from 5 10−10 to 10−4M) or CL 218,872 (ranging from 5 10−9 to 10−4M), respectively. Displacement curves were fit (LIGAND) to a one-, two-, or three-binding site model. Proportion of different biding sites is given within parenthesis. Results are mean ± S.D. of three experiments.
N.D., not detected.