['The purpose of this study was to identify and characterize Na+-dependent, high affinity glutamate transporter (GLUT) activity in the hypothalamic paraventricular nucleus (PVN) and to compare GLUT activity in PVN of euhydrated versus water-deprived rats.', 'Sprague-Dawley rats were deprived of water for two days before sacrifice. Control rats received water ad libitum. After sacrifice, PVN and cerebrum were removed and synaptosomes were prepared using standard techniques. Glutamate uptake was measured using [3H]-glutamate as substrate, physiological buffer, approximately 100\u2009µg of synaptosomal tissue per assay and a Brandel cell harvester.', 'Glutamate uptake was saturable in PVN synaptosomes from euhydrated, control rats with a Vmax of 541\u2009±\u200922\u2009pmol/min-mg protein (SEM) and Km of 17.6\u2009±\u20093.8\u2009µM (SEM). In contrast, Vmax of glutamate uptake was 808\u2009±\u200958\u2009pmol/min-mg protein in PVN of rats deprived of water for 2 days. This was significantly higher than controls (p<0.001). Km was 21.2\u2009±\u20097.3\u2009µM and not significantly different from controls (NS).'] Does dehydration increase sodium-dependent glutamate uptake by hypothalamic paraventricular nucleus synaptosomes?