Effects of short-term hypoxia on [3H]glutamate release from preloaded hippocampal and cortical synaptosomes.

The effect of short-term hypoxia on the release of [3H]glutamate from preloaded hippocampal and cortical synaptosomes was studied in a rapid superfusion system. The technique minimised the loss of released glutamate by reuptake. The results indicated that the effects of short term hypoxia were qualitatively similar to those reported in previous studies using more long-term hypoxia, but were significantly smaller. The non-Ca(2+)-dependent efflux of glutamate from cortical synaptosomes was increased by hypoxia as was the Ca(2+)-dependent release from hippocampal tissue. Possible mechanisms for these findings were discussed. The small amplitude of these changes in comparison to the effects seen in slowly perfused tissue in vitro and in vivo indicated that the contribution made by changes in neuronal efflux to the overall increase in extracellular glutamate seen in hypoxia is relatively minor.