Regional brain glutamate transport in rats at normal and raised concentrations of circulating glutamate |
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Authors: | Richard A Hawkins M Regina DeJoseph Paul A Hawkins |
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Institution: | (1) Department of Physiology and Biophysics, Finch University of Health Sciences/The Chicago Medical School, 60064 North Chicago, IL, USA |
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Abstract: | the permeability of the blood-brain barrier to glutamate was measured by quantitative autoradiography in brains of control rats (average plasma glutamate concentration of 95 ) and rats infused with glutamate (average plasma glutamate concentration of 837 m). Measurements of glutamate permeability were initiated by the injection of 14C]glutamate and stopped at 1 min to avoid the accumulation of 14C]glutamate metabolites. Glutamate entered the brain at a slow rate, with an average permeability-surface area product of 7 l.min...g-1, except in those areas known to have fenestrated capillaries. Glutamate accumulated in the choroid plexus of ventricles, but did not seem to enter the cerebrospinal fluid in detectable amounts regardless of the circulating concentration. Glutamate accumulated in circumventricular organs, such as the median eminence, where the radioactivity was localized without detectable spread. Infusion of glutamate to create high plasma concentrations did not result in greater spread of 14C]glutamate beyond the immediate vicinity of the circum ventricular organs. |
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Keywords: | Autoradiography Glutamic acid transport Blood-brain barrier Dicarboxylic acid Rat (Long Evans) |
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