Abstract
GLUTAMATE uptake into glial cells helps to keep the brain extracellular glutamate concentration, [glu]0, below levels that kill neurons. Uptake is powered1–4 by the transmembrane gradients of Na+, K+ and pH. When the extracellular [K+] rises in brain ischaemia, uptake reverses, releasing glutamate into the extracellular space5,6. Here we show, by monitoring glutamate transport electrically and detecting released glutamate with ion channels in neurons placed outside glial cells, that a raised [H+] inhibits both forward and reversed glutamate uptake. No electroneutral reversed uptake was detected, contradicting the idea7 that forward and reversed uptake differ fundamentally. Suppression of reversed uptake by the low pH occurring in ischaemia8,9 will slow the Ca2+-independent release of glutamate10 which can raise [glu]0 to a neurotoxic level 11,12, and will thus protect the brain during a transient loss of blood supply.
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Billups, B., Attwell, D. Modulation of non-vesicular glutamate release by pH. Nature 379, 171–174 (1996). https://doi.org/10.1038/379171a0
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DOI: https://doi.org/10.1038/379171a0
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