| Assay Method Information | |
| | Ca2+ Mobilization In Vitro Assay |
| Description: | About 24 hrs before an experiment, 5×10^4 cells/well were seeded in poly-D-lysine coated, black/clear-bottomed 96-well plates. The cells were loaded with 2.5 μM Fluo-4AM in loading buffer (1×HBSS, 20 mM HEPES) for 1 hr at 37° C. and washed five times with loading buffer. The cells were transferred into a Functional Drug Screening System 7000 (Hamamatsu, Paris, France), and 11 half logarithmic serial dilutions of test compound at 37° C. were added and the cells were incubated for 10-30 min. with on-line recording of fluorescence. Following this pre-incubation step, the agonist (2S)-2-amino-4-phosphonobutanoic acid (L-AP4) was added to the cells at a concentration corresponding to EC20 with on-line recording of fluorescence; in order to account for day-to-day variations in the responsiveness of cells, the EC20 of L-AP4 was determined immediately ahead of each experiment by recording of a full dose-response curve of L-AP4. Responses were measured as peak increase in fluorescence minus basal (i.e. fluorescence without addition of L-AP4), normalized to the maximal stimulatory effect obtained with saturating concentrations of L-AP4. Graphs were plotted with the % maximal stimulatory using XLfit, a curve fitting program that iteratively plots the data using Levenburg Marquardt algorithm. The single site competition analysis equation used was y=A+((B−A)/(1+((x/C)D))), where y is the % maximal stimulatory effect, A is the minimum y, B is the maximum y, C is the EC50, x is the log 10 of the concentration of the competing compound and D is the slope of the curve (the Hill Coefficient). From these curves the EC50 (drug concentration at which 50% of the maximal receptor activation was achieved), the Hill coefficient as well as the maximal response in % of the maximal stimulatory effect obtained with saturating concentrations of L-AP4 were calculated (see FIG. 1). |
| Affinity data for this assay | |
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