Ultima gold xr liquid scintillation cocktail

Radioligand competition binding was conducted as described previously
(Abadji et al., 1994 (link); Abadji et al., 1999 (link); Murphy and Kendall, 2003 (link)) with some adjustments. Typically, 5
μg of protein membrane was incubated in a shaking water bath for 1 h at
30°C in 200 μl consisting of 1.5 nM [³H]CP55,940 (150.2
Ci/mmol; PerkinElmer Life Sciences, Waltham, MA USA), TME buffer and 0.2%
(vol/vol) bovine serum albumin (BSA), TME buffer and 7% (w/v) sucrose, and 2
μl of the unlabeled ligand in nine concentrations ranging from 0.1
μM to 1 mM. Non-specific binding was determined using 10 μM
CP55,940 in DMSO, in place of the radiolabeled ligand. The reactions are
terminated with the addition of 300 μl of TME and 5% BSA (w/v) then
washed with TME buffer and filtered with a Brandel cell harvester using Whatman
GF/C filter paper. The filter paper samples are placed in scintillation vials
with 4 ml Ultima Gold XR liquid scintillation cocktail (PerkinElmer Life
Sciences, Waltham, MA USA) and counted with a Beckman Coulter 6500 liquid
scintillation counter.