Competition Assays for Di and D2 Dopamine Receptors

Dopamine receptors belong to the group of G protein-coupled receptors (GPCRs) 

With the data obtained in this way competition curves could be generated for (+)-butaclamol (Fig. 7.7). A number of other dopamine antagonists were studied 

Nevertheless, they easily allowed the determination of IC50 values of the test compounds and the calculation of the respective K values [according to Eq. (7), Section 7.3.1, Table 7.2]. 

The reliability of the SPE-LC-ESI-MS/MS quantitation method of the nonbound marker spiperone was verified in identical binding assays employing [ H] spiperone as marker and (S)-sulpiride as test compound, again quantifying the nonbound marker but this time by scintillation counting. Both the run of the competition curve and the Ki value determined for (S)-sulpiride were in good accordance with the results from the MS binding assays (Table 7.2). 

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