Potassium and veratrine-stimulated l-[(3)H]cysteine sulfinate and l-[(3)H]glutamate release from rat brain slices.

The release of l-[(3)H]cysteine sulfinic acid, l-[(3)H]glutamatic acid and [(3)H]GABA from preloaded slices of various rat brain regions in response to either 30 mM K(+) or veratrin was investigated. All these aminoacids were released by both depolarizing agents, which did not produce any changes in the spontaneous efflux of [(3)H]lysine. The K(+) stimulated cysteine sulfinate release from superfused slices was found partly Ca(2+)-dependent in the subiculum, and mainly Ca(2+)-independent in the hippocampus whereas the K(+)-elicited glutamate release was partly Ca(2+)-dependent in both regions. The veratrine-induced release of both cysteine sulfinate and glutamate was blocked by verapamil in a dose-dependent way, although a small verapamil concentration independent release remained. The release pattern of both amino acids was heterogeneous, but roughly correlated among brain regions, except in the subiculum and hypothalamus. These findings demonstrate the releasability of both substances from various brain regions and suggest that those releases occur from different pools, being probably mainly of neuronal origin. They give further evidence that cysteine sulfinate as well as glutamate may serve a neurotransmitter role in the CNS.