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.

BRAIN MITOCHONDRIA. I. ISOLATION OF BOVINE BRAIN MITOCHONDRIA

Two methods of preparing a mitochondrial fraction from beef brain cortex are described. Data are presented on the rate of oxidation of substrates, P/O and respiratory control ratios, cholinesterase activity, and DNA content. Electron micrographs of isolated mitochondria and mitochondria in situ are shown. Comparisons are drawn between these preparations and mitochondria prepared in 0.25 M sucrose. The data on enzymic properties and contamination by non-mitochondrial material indicate that mitochondrial fractions which compare favorably with those from other tissues can be prepared from brain tissue.