Characterization of binding sites for two classes of calcium channel antagonists in human forebrain.

1,4-Dihydropyridine ([3H]PN200-110) and phenylalkylamine ([3H](-)D-888) bound with high affinity to human brain cortex homogenates. The ligand selectivity pattern indicates that [3H]PN200-110 binding was inhibited by related 1,4-dihydropyridine analogues but not by phenylalkylamines. On the other hand, phenylalkylamines were potent inhibitors of [3H](-)D-888 binding in human brain. The radioautographic distribution of [3H]PN200-110 and [3H](-)D-888 binding sites demonstrates that 1,4-dihydropyridine and phenylalkylamine sites were similarly distributed in human forebrain.