An iodinated ligand identifying the D-1 dopamine receptor.

Iodination (with 125I) of SKF 83692 (2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin-7-ol) produces a ligand of high specific activity. In the caudate nucleus of rat brain, this ligand binds to a site which discriminates between the active and inactive enantiomers of drugs selective for the D-1 receptor but which does not recognize drugs selective for the D-2 dopamine receptor or a serotonin receptor. Non-specific binding of this ligand is less than 5% of the total binding.