[3H]Nitrendipine binding sites are decreased in the substantia nigra and striatum of the brain from patients with Parkinson's disease.

We examined the degree of binding of the calcium antagonist, [3H]nitrendipine ([3H]NDP), in the prefrontal cortex, caudate nucleus, putamen, pallidum and substantia nigra obtained at autopsy from patients with Parkinson's disease. The specific bindings of [3H]NDP were significantly reduced in the caudate nucleus, putamen and substantia nigra, as compared to the relevant controls. Scatchard analyses revealed that these reductions resulted from decreases in the apparent maximum number of binding sites (Bmax). The affinity constants (Kd) remained unchanged. Thus, it is highly likely that calcium channel antagonist binding sites on nigral dopamine (DA) neurons may be lost in the degenerative process of Parkinson's disease.