Autoradiographic localization of calcium channel antagonist receptors in rat brain with [3H]nitrendipine.

In vitro autoradiographic techniques have been used to localize [3H]nitrendipine binding sites in the rat brain. The superficial cerebral cortex, the ventral, lateral and posterior nuclei of the thalamus, the molecular layer of the dentate gyrus, the substantia nigra and the external plexiform layer of the olfactory bulb, all contain high densities of silver grains. The level of binding sites are greatly reduced in areas low in synaptic connections. The corpus callosum, the fimbria, the alveus hippocampi and the dorsal commissure of the fornix all lack specific silver grains, as does the lateral olfactory tract of the olfactory bulb. Specific silver grains are not found in the habenula or the hypothalamus. Grains are not associated with blood vessel profiles. The discrete localizations of [3H]nitrendipine binding sites suggest a specific synaptic role.