FREE-FLOW ELECTROPHORETIC SEPARATION AND ELECTRICAL SURFACE PROPERTIES OF SUBCELLULAR PARTICLES FROM GUINEA PIG BRAIN

Continuous free-flow electrophoretic separation has been used to obtain relatively pure preparations of synaptosomes and synaptic vesicles from crude fractions of guinea pig brain homogenates. Measurements of the contents of protein, neuraminic acid, and bound acetylcholine; the activities of succinic dehydrogenase, adenosine triphosphatase, choline acetylase, and 5'-nucleotidase; and the uptake of 14C-labeled choline arid acetylcholine in the presence and absence of hemicholinium, all confirm the electron microscope evidence that the electrophoretic preparations are at least as pure as those obtained by ultracentrifugal methods. The electrophoretic mobility measurements have been used to calculate zeta potentials and surface charge densities for these particles.

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Stimulation of the production of unesterified fatty acids in nerve endings of guinea-pig brain in vitro by noradrenaline and 5-hydroxytryptamine

Biochemical Journal ◽

10.1042/bj1260575 ◽

1972 ◽

Vol 126 (3) ◽

pp. 575-585 ◽

Cited By ~ 17

Author(s):

C. J. Price ◽

C. E. Rowe

Keyword(s):

Fatty Acids ◽

Cerebral Cortex ◽

Guinea Pig ◽

Synaptic Vesicles ◽

Nerve Endings ◽

Synaptic Membranes ◽

Pig Brain ◽

Guinea Pig Brain ◽

Stimulation Of

1. Noradrenaline (1mm) and 5-hydroxytryptamine (1mm) stimulated the production of unesterified palmitate, oleate, stearate and arachidonate in nerve endings (synaptosomes) isolated from combined guinea-pig cerebral cortex and cerebellum. 2. Iproniazid phosphate (0.36mm) increased the concentrations of the same acids in osmotically ruptured synaptosomes. Further addition of 1mm-noradrenaline or 1mm-5-hydroxytryptamine reversed this increase. 3. Noradrenaline (0.01mm) stimulated the production of unesterified fatty acids in isolated synaptic membranes. 5-Hydroxytryptamine (0.01mm) stimulated the production of unesterified fatty acids in synaptic membranes and synaptic vesicles.

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THE ENCEPHALOMYELITIC ACTIVITY OF MYELIN ISOLATED BY ULTRACENTRIFUGATION

Journal of Experimental Medicine ◽

10.1084/jem.115.4.777 ◽

1962 ◽

Vol 115 (4) ◽

pp. 777-788 ◽

Cited By ~ 239

Author(s):

Robert H. Laatsch ◽

Marian W. Kies ◽

Spencer Gordon ◽

Ellsworth C. Alvord

Keyword(s):

Guinea Pig ◽

Basic Protein ◽

Specific Activity ◽

Extraction Procedure ◽

Succinic Dehydrogenase ◽

Electron Microscopic ◽

Pig Brain ◽

And Function ◽

Encephalitogenic Activity ◽

Guinea Pig Brain

A relatively simple preparation of guinea pig brain myelin, free of gross contamination by other cellular elements has been described. Electron microscopic evidence of the predominance of membranous (lamellar) forms was used as the criterion of purity of this fraction. The slight mitochondrial contamination of the myelin fraction was confirmed by its low succinic dehydrogenase activity. Quantitative bio-assay of the encephalitogenic activity of myelin showed it to have a higher specific activity than whole guinea pig brain. The low encephalomyelitic activity of the other subcellular constituents (nuclei and mitochondria) which were removed from myelin by ultracentrifugation in 30 per cent sucrose could be explained by a small amount of myelin contamination. A basic protein of high specific encephalitogenic activity has been isolated from myelin by methods previously applied to whole brain. Although the protein is similar to nuclear histones, the following facts point to certain significant differences. Nuclei prepared by a different procedure from the one developed for the isolation of myelin were found to be non-encephalitogenic. Although basic protein could be extracted readily from these nuclei by dilute HCl, the same extraction procedure yielded little extractable protein from whole myelin. Myelin which had been defatted by cold chloroform-methanol yielded a basic protein which was highly encephalitogenic. The evidence presented thus supports the view that there exists in myelin a new basic protein responsible for the induction of experimental allergic encephalomyelitis, which is distinctly different from nuclear histones. The possible relationship of this protein to myelin structure and function has been discussed.

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The stimulation by transmitter substances and putative transmitter substances of the net activity of phospholipase A2 of synaptic membranes of cortex of guinea-pig brain

Biochemical Journal ◽

10.1042/bj1480197 ◽

1975 ◽

Vol 148 (2) ◽

pp. 197-208 ◽

Cited By ~ 29

Author(s):

R J Gullis ◽

C E Rowe

Keyword(s):

Guinea Pig ◽

Phospholipase A2 ◽

Synaptic Vesicles ◽

Optimum Concentration ◽

Synaptic Membranes ◽

Phospholipase A1 ◽

Response Curves ◽

Pig Brain ◽

Hydrolysis Of ◽

Guinea Pig Brain

1. The distribution of the hydrolyses of phosphatidylcholine by phospholipase A2 and phospholipase A1, and the hydrolysis of lysophosphatidylcholine by lysophospholipase, in subcellular and subsynaptosomal fractions of cerebral cortices of guinea-pig brain, was determined. 2. Noradrenaline stimulated hydrolysis by phospholipase A2 in whole synaptosomes, synaptic membranes and fractions containing synaptic vesicles. 3. Stimulation of hydrolysis by phospholipase A2 in synaptic membranes by noradrenaline was enhanced by CaCl2, and by a mixture of ATP and MgCl2. The optimum concentration of CaCl2, in the presence of ATP and MgCl2, for stimulation by 10 muM-noradrenaline was in the range 1-10muM. The optimum concentration for ATP-2MgCl2 in the presence of 1 muM-CaCl2 was in the range 0.1-1mM. 4. Hydrolysis by phospholipase A2 of synaptic membranes was also stimulated by acetylcholine, carbamoylcholine, 5-hydroxytryptamine, dopamine (3,4-dihydroxyphenethylamine), histamine, psi-aminobutyric acid, glutamic acid and aspartic acid. With appropriate concentrations of cofactors, sigmoidal dose-response curves were obtained, half-maximum stimulations being obtained with concentrations of stimulant in the range 0.1-1muM. 5. Taurine also stimulated hydrolysis of phosphatidylcholine by phospholipase A2. There were only slight stimulations with methylamine, ethylenediamine or spermidine. No stimulation was obtained with glucagon.

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