An Activation of Synaptosomal Na+, K+‐ATPase by a Novel Dibenzoxazepine Derivative (BY‐1949) in the Rat Brain: Its Functional Role in the Neurotransmitter Uptake Systems

: In search of factors mitigating the final outcome of ischemic and epileptic brain damage, we tested a novel dibenzoxazepine derivative (BY‐1949), as the compound has been shown to be effective under these two conditions. First, using rat brain, we assessed whether or not BY‐1949 affects the Na+,K+‐ATPase activity. Although in vitro applications of either BY‐1949 or its three major metabolites did not cause any apparent effects, both acute and chronic oral administrations of the compound (10 mg/kg) invariably increased the Na+,K+‐ATPase activity in the synaptosomal plasma membranes by increasing Vmax values. Second, it was shown by this study that the drug treatment caused marked increases in the uptake of both glutamic acid and γ‐aminobutyric acid into the synaptosomes. These results suggest that the activity against ischemic/epileptic brain damage by BY‐1949 is explicable, at least partly, in terms of improvement of ionic derangements across the neural membranes via Na+,K+‐ATPase activation.