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CHLOROTETRACYCLINE AS AN INDICATOR OF THE INTERACTION OF CALCIUM WITH BRAIN MEMBRANE FRACTIONS
Author(s) -
Carvalho C. A. M.
Publication year - 1978
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.1471-4159.1978.tb12410.x
Subject(s) - membrane , fluorescence , chemistry , calcium , biophysics , quantum yield , choline , myelin , synaptosome , yield (engineering) , biochemistry , chromatography , biology , central nervous system , organic chemistry , physics , materials science , quantum mechanics , neuroscience , metallurgy
— The fluorescence of chlorotetracycline (CTC) in the presence of synaptosomes isolated from sheep brain is selectively increased by Ca 2+ under conditions in which Mg 2+ , Na + , K + , Li + or choline have only a small effect. The monovalent cations release bound Ca 2+ from synaptosomes, and this effect is reflected by a decrease in the CTC fluorescence. Under optimal conditions there is a near parallelism between Ca 2+ and CTC binding to the synaptosomes membranes, and Li + is the monovalent cation tested which interferes the most with the binding of both substances. These results obtained in a predominantly sucrose medium become less distinct when media simulating physiological composition are utilized, which limits the usefulness of the method. Brain mitochondria and myelin also bind Ca 2+ and CTC. The ratio of the fluorescence signal (or CTC bound) to Ca 2+ bound is highest of all for mitochondrial membranes, and the apparent fluorescence quantum yield of CTC is also the highest in these membranes, which suggests that the Ca 2+ in these membranes is localized in a more apolar region than is the case for synaptosomes and myelin.