Table 2

Concentration-dependent actions of EEDQ on receptor density and function in CHO-hD3 membranes

EEDQReceptor Saturation[35S]GTPγS Bound
KDBmax
μM nM % of control % of control
01.18  ± 0.19100100
101.38  ± 0.0171.5  ± 9.377.5  ± 8.7
331.31  ± 0.0347.7  ± 7.651.2  ± 1.6
1001.24  ± 0.1132.0  ± 4.744.9  ± 2.0
3001.33  ± 0.0918.7  ± 6.433.6  ± 5.6

CHO-hD3 cell membranes were treated with different concentrations of EEDQ. Receptor density was determined in [125I]iodosulpiride saturation binding experiments. Percentage of remaining hD3 binding sites is calculated as a percentage of mean Bmax determined in absence of EEDQ (15.43 pmol/mg, Table 1). [35S]GTPγS binding is expressed as percentage of dopamine (10 μM)-dependent binding observed under control conditions in parallel experiments.