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

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.