RECEPTOR-RECEPTOR LINK IN MEMBRANES REVEALED BY LIGAND COMPETITION - EXAMPLE FOR DOPAMINE D-1 AND D-2 RECEPTORS

An interaction or link between dopamine D1 receptors and dopamine D2 receptors was found by a ligand competition method, using [H-3]raclopride to label dopamine D2 receptors and SCH 23390 to block dopamine D1 receptors. In the presence of endogenous or exogenous dopamine, SCH 23390 increased the binding of [H-3]raclopride in post-mortem human striata homogenates or in tissue culture cells containing human dopamine D1 and D2 receptors. In order to reveal such intramembrane receptor-receptor interactions in general, therefore, it appears essential to add two agonists, one for each receptor, and then to block one of the receptors when measuring the binding of a ligand to the second receptor. (C) 1994 Wiley-Liss, Inc.