The effects of anaesthetic and convulsant barbiturates on the efflux of [3H]D-aspartate from brain minislices.

The effects have been investigated of anesthetic and convulsant barbiturates on the spontaneous and potassium-stimulated efflux of [3H]D-aspartate from rat cortex minislices. In concentrations (100 microM) which have previously been shown to alter calcium ATPase activity in synaptosomes, anaesthetic barbiturates depressed and convulsant barbiturates stimulated the spontaneous efflux of [3H]D-aspartate in a dose-dependent manner. The effects on the efflux of [3H]D-aspartate evoked by 44.7 mM KCl were similar, although one convulsant barbiturate (1,3M1B) was without effect. The results are discussed in terms of entry and removal of calcium ions from nerve terminals.