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ISOLATION OF [ 3 H]ACETYLCHOLINE POOLS BY SUBCELLULAR FRACTIONATION OF CEREBRAL CORTEX SLICES INCUBATED WITH [ 3 H]CHOLINE
Author(s) -
Richter Judith A.,
Marchbanks R. M.
Publication year - 1971
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1971.tb12000.x
Subject(s) - vesicle , acetylcholine , choline , cytoplasm , cell fractionation , incubation , synaptic vesicle , chemistry , biochemistry , sephadex , specific activity , cerebral cortex , stimulation , fractionation , biophysics , chromatography , biology , membrane , enzyme , endocrinology
— Subcellular fractions were isolated from tissue incubated in [ 3 H]choline with or without the addition of 33 mM‐KCl. Radioactive and bioassayable ACh were measured in the synaptosomes, synaptosomal cytoplasm and in the vesicles. After incubation with KCI the vesicles, as isolated, contained ACh of a lower specific activity than the cytoplasmic ACh. Therefore the vesicle fraction as isolated does not represent the source of the high specific activity ACh released upon K + stimulation. However the vesicle fraction is heterogeneous. Most of the bioassayable ACh but little of the radioactive ACh in the vesicles passed through iso‐osmotic Sephadex columns. These results raise the question of the existence of vesicles which contain highly radioactive ACh but which lose it during their isolation by current methods. Different possible forms of heterogeneity are discussed.