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Ionizing Radiation Alters the Properties of Sodium Channels in Rat Brain Synaptosomes
Author(s) -
Mullin Michael J.,
Hunt Walter A.,
Harris R. Adron
Publication year - 1986
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.1471-4159.1986.tb04528.x
Subject(s) - veratridine , ionizing radiation , biophysics , chemistry , sodium channel , batrachotoxin , sodium , synaptosome , membrane , irradiation , biochemistry , biology , nuclear physics , physics , organic chemistry
The effect of ionizing radiation on neuronal membrane function was assessed by measurement of neurotoxin‐stimulated 22 Na + uptake by rat brain synaptosomes. High‐energy electrons and γ photons were equally effective in reducing the maximal uptake of 22 Na + with no significant change in the affinity of veratridine for its binding site in the channel. Ionizing radiation reduced the veratridine‐stimulated uptake at the earliest times measured (3 and 5 s), when the rate of uptake was greatest. Batrachotoxin‐stimulated 22 Na + uptake was less sensitive to inhibition by radiation. The binding of [ 3 H]saxitoxin to its receptor in the sodium channel was unaffected by exposure to ionizing radiation. The effect of ionizing radiation on the lipid order of rat brain synaptic plasma membranes was measured by the fluorescence polarization of the molecular probes 1,6‐diphenyl‐1,3,5‐hexatriene and l‐[4‐(trimethylammonium)phenyl]‐6‐phenyl‐l,3,5‐hexatriene. A dose of radiation that reduced the veratridine‐stimulated uptake of 22 Na + had no effect on the fluorescence polarization of either probe. These results demonstrate an inhibitory effect of ionizing radiation on the voltage‐sensitive sodium channels in rat brain synaptosomes. This effect of radiation is not dependent on changes in the order of membrane lipids.