The efflux from nervous tissue of presumptive amino acid transmitters was studied by superfusing rat spinal cord slices preloaded with [14C]glycine and 3H-GABA. The rate of efflux of the amino acids was slower than that of urea and was retarded by superfusion at 4°C. Extracellular glycine exchanged with intracellular [14C]glycine, but did not affect the rates of efflux of labeled GABA, proline, l-lysine, or cycloleucine. The efflux of [14C]glycine was accelerated by extracellular GABA, unaffected by extracellular AIB or proline, and retarded by extracellular l-lysine and l-leucine. Ouabain increased the rate of efflux of [14C]glycine and 3H-GABA, but did not affect [14C]urea efflux. Cyanide stimulated the efflux of [14C]glycine but not 3H-GABA. The rates of efflux of both amino acids were increased in Ca-free medium containing EDTA, unchanged in 30 mM K medium, and decreased in low Na medium. The results indicate that there are mediated transport systems with considerable specificity which regulate the efflux of glycine and GABA across neural membranes.
|Original language||English (US)|
|Number of pages||19|
|State||Published - Dec 24 1971|
ASJC Scopus subject areas
- Molecular Biology
- Clinical Neurology
- Developmental Biology