Klaas Kramer

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Functional reconstitution of the N-methyl-D-aspartate (NMDA) receptors was achieved by adding synaptic membranes from rat brain to large planar bimolecular lipid membranes (BLMs). The reconstituted receptors exhibited several properties of the NDMA receptors described using a variety of biochemical and electrophysiological techniques. Addition of NMDA at(More)
Potassium at low concentrations was found to inhibit the Na-dependent [3H]L-glutamate binding to rat hippocampal synaptic membranes. This inhibition was probably due to a competition between potassium and sodium at the ionic locus of the recognition site for glutamate of the uptake process. In addition, potassium inhibited the high-affinity [3H]L-glutamate(More)
This study aimed to assess the time needed by rats, which had not been previously transported, to acclimate to a new environment after 5 h of van transport, using physiological parameters as measures of acclimatization. Animal shipping boxes and transport van conditions were standardized to minimize stress factors that could be associated with transport.(More)
Some experimental procedures are associated with placement of animals in wire-bottom cages. The goal of this study was to evaluate stress-related physiological parameters (heart rate [HR], body temperature [BT], locomotor activity [LA], body weight [BW] and food consumption) in rats under two housing conditions, namely in wire-bottom cages and in(More)
Transportation of laboratory rodents unavoidably causes stress. Nevertheless, very little is known about the effects of transportation and how long it takes for the animal to recuperate. In the present study, we investigated physiological and behavioral parameters before and after transportation in both transported and nontransported animals. We took blood(More)
Most laboratory animals used in research are vendor-bred and transferred to research facilities. Transfer procedures might have considerable and unintended effects on research results. In the present study we compared physiological and behavioral parameters before and after external and internal transfer, as well as between transferred and non-transferred(More)
Transfer from the breeding facility to a research facility is a stressful event for laboratory animals. Heat stress has been reported to constitute one of the major concerns during transport of animals. This study measured ambient and body temperature, corticosterone and glucose levels, body weight, behavior and water and food intake before, during and(More)
Previous studies have indicated that calcium ions induce an irreversible increase of [3H]glutamate binding to rat hippocampal membranes. The present study was intended to provide an estimate of the time-course for this effect. The calcium chelator EGTA and the proteinase inhibitor leupeptin were introduced at various times during the incubation of(More)
The properties of excitatory amino acid receptors in hippocampal slices were analyzed using agonist-induced stimulation of 22Na efflux rate. Several amino acids (L- and D-glutamate, N-methylaspartate) produce progressively smaller responses upon successive applications, whereas D,L-homocysteate does not. Several lines of evidence suggest that depletion of(More)
The effects of excitatory amino acids on 22Na efflux rate in rat hippocampal slices were determined at various postnatal days and following removal of a major afferent system. Two weeks after a unilateral hippocampal aspiration, the 22Na efflux induced by potassium ions, D-glutamate, N-methylaspartate, and kainate is significantly decreased in the(More)
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