[3H]Quinpirole | [3H]Raclopride | ||||
---|---|---|---|---|---|
Affinity (nM) | Bmax (pmol/g protein) | Affinity (nM) | Bmax (pmol/g protein) | ||
D3 | Untreated | 1.34 ± 0.243-a | 3920 ± 3703-a | 1.02 ± 0.09 | 3410 ± 40 |
High | 0.57 ± 0.12 | 1530 ± 270 | |||
Low | 4.4 ± 1.3 | 3140 ± 320 | |||
PTX treated | 2.74 ± 0.23 | 1230 ± 100 | 1.18 ± 0.19 | 1150 ± 70 | |
D2A | Untreated | 4.20 ± 0.70 | 180 ± 20 | 1.06 ± 0.03 | 990 ± 70 |
PTX treated | NS | NS | 1.10 ± 0.05 | 790 ± 60 |
The radioligand binding studies were performed and the dissociation constants (Kd) and receptor densities (Bmax) were calculated as described in “Methods.”
The results are means ± S.E.s of three to four experiments. The buffer contained 50 mM Tris-HCl, 1 mM EDTA, 5 mM KCl, 4 mM MgCl2 and 120 mM NaCl for the [3H]raclopride binding or 120 mM NMDG for the [3H]quinpirole binding. High and low represent the Kd and Bmax values of high and low affinity agonist binding site, respectively. PTX; pertussis toxin. NS; no specific binding.
↵3-a Values analyzed by a one-site model. A significantly better fit was achieved with a two-site model.