| Assay Method Information | |
| | Binding Assay |
| Description: | Binding affinity (Ki) for the compounds was measured by inhibition of radioligand binding to membranes from CHO cells expressing human M4 receptor. Membranes were prepared by nitrogen cavitation and differential centrifugation as previously described (Hoare et al., Mol. Pharmacol. 2003 March; 63(3): 751-65). The radioligand employed was tritiated N-methylscopolamine, used at a concentration of 1.5 nM. A dose-response of twelve concentrations of compound was used, ranging from 10 μM to 32 μM. The assay buffer was 50 mM HEPES, 100 mM NaCl, 5 mM MgCl2, 1 mM ethylenediaminetetraacetic acid, pH-adjusted to pH 7.4. Membranes, radioligand and compound were incubated together for 90 minutes at 37° C., in a total volume of 150 μL in a 96-well plate. Receptor-bound radioligand was then collected by harvesting the assay over glass fiber filters pretreated with polyethylenimine to trap the cell membranes, using rapid vacuum filtration. Harvesting and radioactivity counting was conducted as previously described (see, e.g., Hoare et al., Mol. Pharmacol. 2003 63(3):751-65); Erratum at Mol. Pharmacol. 2005 July; 68(1): 260). |
| Affinity data for this assay | |
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