Acetylcholine and cholinacetylase content of synaptic vesicles.

Acetylcholine, cholinacetylase, and acetylcholinesterase were determined in three subfractions that resulted from the osmotic shock of the "mitochondrial" fraction of the rat brain. Acetylcholine and cholinacetylase were found concentrated in the subfraction that contained mainly synaptic vesicles and some membranes, whereas the larger proportion of the acetylcholinesterase was observed in the subfraction that contained torn nerve endings. These results support the idea that synaptic vesicles are the morphological units of acetylcholine within the synapse.