Magnesium ions reveal nanomolar potency of dopamine at [3H]spiperone labelled D-2 receptors in rat corpus striatum.
DJ De Vries, PM Beart
Eur J Pharmacol | Published : 1985
Preparation and assay of rat striatal membranes in the presence of 10 mM magnesium ions resulted in an IC50 value constant for dopamine of 13 nM at D-2 dopamine receptors labelled by [3H]spiperone. Inclusion of 100 microM GTP under these conditions resulted in a 13 fold decrease in dopamine displacing potency. Displacing potencies for dopamine in the nanomolar range are associated with agonist-specific D-3 receptor binding and it is predicted that the component of D-2 binding with high agonist affinity may play a confounding role in many D-3 receptor studies.