EFFECTS OF POTASSIUM AND GLUTAMATE ON BRAIN CORTEX SLICES: UPTAKE AND RELEASE OF GLUTAMIC AND OTHER AMINO ACIDS

Effects of an increased concentration of K+ (55 mm) in the medium on fluxes of glutamate and other amino acids in the presence and absence of 10 mm‐glutamate were studied.

Abstract

Abstract— Effects of an increased concentration of K + (55 m m ) in the medium on fluxes of glutamate and other amino acids in the presence and absence of 10 m m ‐glutamate were studied. The following observations were made: (1) The efflux of glutamate is slightly increased by excess K + . The glutamate efflux is smaller than the potassium fluxes. (2) The K + ‐induced increase of glutamate efflux is enhanced under anoxia or in glutamate‐containing media. (3) The influx of glutamate is unaffected or slightly increased by excess K + . (4) The efflux of GABA is increased by excess K + , both in the absence and in the presence of glutamate. (5) Efflux of glutamine, leucine and lysine is increased by excess K + , but only provided that glutamate is also present in the medium. (6) Efflux of glutamate and of GABA is increased by addition of 10 m m ‐glutamate.