Assay Method Information

Assay Name:  Human D1 Binding Assay
Description:  The assay was performed as a SPA-based competition-binding in a 50 mM Tris pH 7.4 assay buffer containing 120 mM NaCl, 5 mM KCl, 4 mM MgCl2, 1.5 mM CaCl2, and 1 mM EDTA. Approximately 1 nM 3H-SCH23390 (Perkin Elmer, NET 930) was mixed with test compound before addition of 2.5 μg of a homogenized human D1 receptor membrane preparation and 0.25 mg SPA beads (WGA RPNQ 0001, Amersham) in a total volume of 60 μL.The assay plates were under agitation incubated for 60 minutes at room temperature before the plates were centrifuged and subsequently counted in a scintillation counter (TriLux, Wallac). The total binding, which comprised approximately 15% of added radioligand, was defined using assay buffer, whereas the non-specific binding was defined in the presence of 10 haloperidol.Data points were expressed in percent of the specific binding and the IC50 values (concentration causing 50% inhibition of specific binding) and were determined by non-linear regression analysis using a sigmoidal variable slope curve fitting. The dissociation constant (Ki) was calculated from the Cheng Prusoff equation (Ki=IC50/(1+(L/KD)), where the concentration of free radioligand L is approximated to the concentration of added radio-ligand in the assay.
Affinity data for this assay
 

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