Effect on cerebral D-[3H]aspartate release of 3-mercaptopropionic acid and methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate.

Minislices of rat brain cortex were preloaded with D-[3H]aspartate and spontaneous and potassium-induced (25 mM KCl) efflux of labelled compound into superfusate measured. 3-Mercaptopropionic acid, 100-220 microM did not modify the spontaneous efflux of D-[3H]aspartate, but augmented the K+-induced efflux. Methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate, 10 or 100 microM, enhanced both spontaneous and K+-induced efflux of D-[3H]aspartate. The convulsant action of both compounds may be due to enhanced synaptic release of aspartate or a related excitatory neurotransmitter.