• DOI:10.1111/j.1471-4159.1965.tb04237.x
• Corpus ID: 5746357

THE MORPHOLOGY AND ACETYLCHOLINE CONTENT OF ISOLATED CEREBRAL CORTICAL SYNAPTIC VESICLES

@article{Whittaker1965THEMA,
  title={THE MORPHOLOGY AND ACETYLCHOLINE CONTENT OF ISOLATED CEREBRAL CORTICAL SYNAPTIC VESICLES},
  author={Victor P. Whittaker and Michael N. Sheridan},
  journal={Journal of Neurochemistry},
  year={1965},
  volume={12}
}

• V. P. Whittaker, M. Sheridan
• Published 1 May 1965
• Biology, Chemistry
• Journal of Neurochemistry

WHEN brain tissue is homogenized under carefully controlled conditions, a high proportion of the presynaptic nerve terminals are torn away from their attachments to form discrete particles for which the term ‘synaptosomes’ has recently been adopted (WHITTAKER, MICHAELSON and KIRKLAND, 1964). These particles may be separated from other subcellular brain particles by differential and density gradient centrifuging. They retain all the structural features of the nerve endings, together with their content of transmitter substances. On suspension in hypotonic media, a proportion of them swell and burst, discharging the contents of their cytoplasm. A simple density gradient procedure enables the various components of the synaptosome-soluble cytoplasmic constituents, synaptic vesicles, external membranes and intra-terminal mitochondriato be separated from the disrupted synaptosomes in relatively pure form, thus enabling the compartmentation of transmitter substances and other constituents of the nerve ending to be determined (WHITTAKER et al., 1963, 1964). Synaptosomes were first prepared by HEBB and WHITTAKER (1958) and first identified as such by GRAY and WHITTAKER (1960, 1962; see also WHITTAKER, 1960). The effect of hypotonic disruption was studied by WHITTAKER (1959, 1961), JOHNSTON and WHITTAKER (1963), DE ROBERTIS, RODRIGUEZ DE LORES ARNAIZ, SALGANICOFF, PELLEGRINO DE IRALDI and ZIEHER (1963) and WHITTAKER et al. (1964) (definitive papers only are quoted). The subject has been comprehensively reviewed by WHITTAKER (1964 a, b). This paper describes some further observations which have been made on the morphology and acetylcholine content of pure preparations of isolated synaptic vesicles. In a study of the properties of synaptosomes isolated from various areas of the central nervous system, regional differences in stability were observed during exposure to hypotonic conditions. Synaptosomes from the cerebral cortex were found to be more readily disrupted than those from some other areas and to give a higher yield of synaptic vesicles. Accordingly, cortical tissue was used as the source of synaptic vesicles in the present study. Methods have been devised for determining the average number of acetylcholine molecules/vesicle and the findings are discussed in relation to the problem of the quantized release of acetylcholine at cholinergic nerve endings. Preliminary accounts of this work have been given by SHERIDAN and WHITTAKER (1964) and WHITTAKER (1 964 c).