Rapid regulation of [3H]hemicholinium-3 binding sites in the rat brain

The effects of various drugs known to affect the sodium-dependent high-affinity choline-uptake system (SDHACU) in the brain were examined for their action upon the [3H]hemicholinium-3 [( 3H]HCh-3) binding site, which is associated with the choline carrier. The [3H]HCh-3 binding sites are affected in a similar way to the SDHACU system. Thus, alterations in the velocity of choline-uptake are mediated through changes in the apparent number of available transport sites at cholinergic terminals.