| Assay Method Information | |
| | Radioligand Binding Assay |
| Description: | Radioligand binding assays for cloned muscarinic receptors were performed in 96-well microtiter plates in a total assay volume of 100 μL. CHO cell membranes stably expressing either the hM1, hM2, hM3, hM4 or hM5 muscarinic subtype were diluted in assay buffer to the following specific target protein concentrations (μg/well): 10 μg for hM1, 10-15 μg□for hM2, 10-20 μg□for hM3, 10-20 μg□for hM4, and 10-12 μg□for hM5 to get similar signals (cpm). The membranes were briefly homogenized using a Polytron tissue disruptor (10 seconds) prior to assay plate addition. Saturation binding studies for determining KD values of the radioligand were performed using L-[N-methyl-3H]scopolamine methyl chloride ([3H]-NMS) (TRK666, 84.0 Ci/mmol, Amersham Pharmacia Biotech, Buckinghamshire, England) at concentrations ranging from 0.001 nM to 20 nM. Displacement assays for determination of Ki values of test compounds were performed with [3H]-NMS at 1 nM and eleven different test compound concentrations. The test compounds were initially dissolved to a concentration of 400 μM in dilution buffer and then serially diluted 5× with dilution buffer to final concentrations ranging from 10 pM to 100 μM. The order of addition and volumes added to the assay plates were as follows: 25 μL radioligand, 25 μL diluted test compound, and 50 μL membranes. Assay plates were incubated for 6 hours at 37° C. Binding reactions were terminated by rapid filtration over GF/B glass fiber filter plates (PerkinElmer, Inc.) pre-treated in 1% BSA. Filter plates were rinsed three times with wash buffer (10 mM HEPES) to remove unbound radioactivity. The plates were then air-dried and 50 μL Microscint-20 liquid scintillation fluid (PerkinElmer, Inc.) were added to each well. The plates were then counted in a PerkinElmer Topcount liquid scintillation counter (PerkinElmer, Inc.). |
| Affinity data for this assay | |
|---|---|
| If you find an error in this entry please send us an E-mail | |