Bicarbonate-sensitive cysteine induced elevation of extracellular aspartate and glutamate in rat hippocampus in vitro.
The effect of different concentrations of cysteine (0.125, 0.25, 0.5 and 1 mM) on the net efflux of endogenous amino acids was studied by the incubation of rat hippocampal slices. Addition of cysteine (1 mM) in bicarbonate containing low K+ medium (5 min) selectively increased the basal net efflux of glutamate and aspartate by 370% and 396%, respectively. High K+ media (50 mM) containing cysteine (1 mM) evoked the net efflux of glutamate and aspartate by 1454% and 1019%, respectively. The corresponding effects in control slices without cysteine were 669% and 404%, respectively. No changes were observed on the concentrations of GABA, glutamine and taurine. The cysteine oxidation products, cysteine sulfinate (0.5 microM) and cystine (0.25 mM) were without effects. The effect of cysteine (0.5 mM) was dramatically reduced in media with no added bicarbonate/CO2. Thus, cysteine in a bicarbonate-sensitive manner selectively increases the extracellular concentration of excitotoxic amino acids in adult rat brain in vitro, possibly by interfering with the carrier-mediated glutamate uptake/release.
Abbas
A K
AK
Institute of Anatomy and Cell Biology, University of Göteborg, Sweden.
Jardemark
K
K
Lehmann
A
A
Weber
S G
SG
Sandberg
M
M
D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism*; D001639:Bicarbonates / Q000494:pharmacology*; D003545:Cysteine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D003553:Cystine / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D018377:Neurotransmitter Agents / Q000494:pharmacology; D051381:Rats; D013654:Taurine / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D001639:Bicarbonates; D018377:Neurotransmitter Agents; D013654:Taurine; D001224:Aspartic Acid; D018698:Glutamic Acid; D003553:Cystine; D005680:gamma-Aminobutyric Acid; D003545:Cysteine; C013461:cysteine sulfinic acid