title: Glutamine-induced membrane currents in cultured rat hippocampal neurons.
abstract: Glutamine is present at high concentrations in the extracellular fluid of the brain. It shuttles between glia cells and neurons, and serves as a precursor for both glutamate and gamma-amino butyric acid. Direct actions of glutamine at central neurons are, however, not well understood. Here we showed that L-glutamine (0.5-10 mm) evoked a dose-dependent inward transmembrane current in primarily cultured rat hippocampal neurons. Typical responses were outwardly rectifying and had a reversal potential around 0 mV. The current was partially sensitive towards blockers of ionotropic glutamate receptors and was partially carried by activation of N-methyl-D-aspartate receptors. However, cellular responses to L-glutamine showed clear biophysical and pharmacological differences to L-glutamate-evoked currents. Responses were highly specific for L-glutamine and no responses could be evoked by D-glutamine, L-alanine, L-valine, L-leucine and the system-A-specific agonist alpha-(methylamino)-isobutyric acid. Together, these data indicate that hippocampal neurons can be depolarized by electrogenic effects specific for L-glutamine.
authors.affiliation: Department of Physiology and Pathophysiology, University of Heidelberg, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany.
authors.forename: Sergej
authors.initials: S
authors.lastname: Kolbaev
authors.forename: Andreas
authors.initials: A
authors.lastname: Draguhn
mesh_terms: D000818:Animals; D002712:Chlorides / Q000378:metabolism; D004622:Embryo, Mammalian; D018691:Excitatory Amino Acid Antagonists / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000494:pharmacology*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects* / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
chemical_list: D002712:Chlorides; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D005973:Glutamine; D018698:Glutamic Acid; D012964:Sodium