Electronic Resource
Oxford, UK
:
Blackwell Publishing Ltd
Journal of neurochemistry
15 (1968), S. 0
ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
—(1) A microsomal preparation from rat brain accumulated calcium by an ATP-dependent process during incubation in a hypotonie medium. Accumulation was reduced in media containing 100 mm-NaCl, 100 mm-KCl or 100 mm-choline chloride or 200 mm-sucrose. During prolonged incubations NaCl further decreased calcium content unlike the other ions; this suggests a release of accumulated calcium by NaCl.(2) Microsomes that had accumulated calcium during a prior incubation (‘preloaded microsomes’) lost calcium during a subsequent incubation. NaCl specifically increased the rate of loss of calcium. Ouabain had no effect on the NaCl-induced efflux.(3) Loss of calcium from preloaded microsomes, both with and without NaCl, had a high temperature coefficient. Measurements of monovalent cation content showed no correlation of either the uptake or loss with a simple ion-exchange process and the accumulated calcium did not exchange with calcium in the medium.(4) ATP specifically reduced the efflux of calcium from preloaded microsomes. Although the diminished loss of calcium could be attributed in part to reaccumulation, this was not the only mechanism since ATP also reduced the loss from continuously perfused microsomes preloaded with calcium.(5) A series of neurotropic drugs had little effect on the efflux of calcium. Low concentrations of chlorpromazine decreased calcium retention less than 20 per cent.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1968.tb06841.x
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