pIC50 and Hill coefficient values for dopamine inhibition of [3H]spiperone binding to hD2L-CHO and hD3-CHO-high cell membranes
| pIC50 | Hill Coefficient | |
|---|---|---|
| −logM | ||
| hD2L-CHO | ||
| No GTPγS | 5.60 ± 0.17 | 0.48 ± 0.06 |
| 100 μM GTPγS | 4.87 ± 0.28 | 0.81 ± 0.12 |
| hD3-CHO-high | ||
| No GTPγS | 7.76 ± 0.19 | 0.67 ± 0.05 |
| 100 μM GTPγS | 7.43 ± 0.16 | 0.85 ± 0.09 |
Values were obtained from a one-site fitting of the dopamine inhibition curves. Values represent the mean ± S.D. of five independent experiments, using single determinations.
In the absence of GTPγS, a two-site model better described the data for hD2L-CHO (F-test, p < .05). The pIC50 values were 5.14 ± 0.13 for the low-affinity binding site and 7.20 ± 0.13 for the high-affinity binding site, which represented 27 ± 3% of the total number of binding sites. At hD3-CHO, a two-site model did not improve the fitting of the inhibition curve to the data (F test, p > .05).