Interrelationship between glutamate and membrane-bound ATPases in nerve cells.
Plasma membrane potential generated by Na+, K(+)-ATPase provides the driving force for high-affinity, Na(+)-dependent uptake of glutamate into the cytoplasm of glutamatergic nerve endings and glial cells. Ca2(+)-calmodulin-dependent ATPase in the plasma membrane and Ca2(+)-ATPase in the endoplasmic reticulum influence the intracellular [Ca2+] and, therefore, the exocytotic release of neurotransmitter glutamate. The membrane potential across the membrane of the synaptic vesicles, generated by a H(+)-ATPase, provides the driving force for synaptic vesicular uptake of glutamate as well as that of GABA and glycine. Hypoxia and ischemia lead to release of glutamate, perhaps in consequence of an increased endogenous pool of glutamate and/or lack of substrate (ATP) for the ATPases. This release, rather than being exocytotic, is believed to result mainly from a reversal of the Na(+)-dependent high-affinity glutamate transporter in the plasma membrane.
Torgner
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I
Neurochemical Laboratory, University of Oslo, Norway.
Kvamme
E
E
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D005089:Exocytosis / Q000502:physiology; D005971:Glutamates / Q000378:metabolism*; D009474:Neurons / Q000201:enzymology / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism; D010100:Oxygen / Q000502:physiology; D013574:Synaptosomes / Q000378:metabolism
D005971:Glutamates; D018377:Neurotransmitter Agents; D000251:Adenosine Triphosphatases; D010100:Oxygen