Acetylcholine binding by isolated synaptic vesicles in vitro.

ISOLATED synaptic vesicles have been clearly shown to bind transmitters of the catecholamine type1. The binding of acetylcholine (ACh) by isolated vesicles has not been substantiated. The report by Burton2 that preparations of synaptic vesicles took up radioactive ACh has been criticized on methodological grounds by Marchbanks3, who demonstrated that 14C–ACh exchanges with nerve ending ACh but not vesicular ACh. Kuriyama et al.4, on the other hand, showed that 14C–ACh binds to a purified vesicle fraction from whole mouse brain. This binding may be considered non-specific in that several organic and inorganic ions could prevent or reverse it.