Isolation of synaptosomes and synaptic membranes from the cerebral cortex of the rat, monkey, cat and pig was achieved by centrifugation of the crude mitochondrial fraction through a continuous sucrose gradient using high-speed zonal rotors. Electron microscopy and the activity of certain marker enzymes, such as choline acetyltransferase, acetylcholinesterase and (Na+-K+)-activated ouabin-sensitive ATPase, were used to characterize the various gradient fractions. In all four species studied the synaptosomes were found in the region from 31 to 37% sucrose of the gradient of the crude mitochondrial fraction (P2) and a synaptic plasma membrane fraction was found in the region from 24 to 31% sucrose of the gradient of the lysed crude mitochondrial fraction (P2L). In the case of the rat and monkey there appeared to be some resolution of noncholinergic nerve endings from cholinergic endings.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)