title: Ion channels activated by quinolinic acid in cultured rat hippocampal neurons.
abstract: The membrane responses to quinolinic acid, an excitotoxic brain metabolite, were studied in cultured rat hippocampal neurons with the patch-clamp technique. In the whole-cell recording mode, pressure applications of quinolinic acid elicited inwardly directed membrane currents over a membrane potential range of -60 to -5 mV. The current response reversed at about 0 mV. The current-voltage (I-V) relation of the response had a negative slope conductance at membrane potentials more negative than -40 mV. On removal of Mg2+ from the extracellular solution, the current response showed no region of negative slope conductance at potentials more positive than -60 mV. In Mg2+-free solution applications of quinolinic acid elicited discrete pulse-like current flows through the outside-out membrane patch. The single channel conductance was 40-46 pS over a membrane potential range of -40 to -80 mV, and 50-55 pS at membrane potentials more positive than +30 mV, showing an outward rectification. These values of the single channel conductance were similar to those of the main conducting state of the channels activated by N-methyl-D-aspartate (NMDA). The responses to quinolinic acid were completely suppressed by the NMDA receptor antagonist (+/-)-2-amino-5-phosphonovaleric acid. The results indicate that quinolinic acid selectively activates NMDA receptors in the cultured rat hippocampal neurons.
authors: Department of Physiology, School of Medicine, Gunma University, Japan.
authors: K
authors: K
authors: Tsuzuki
authors: M
authors: M
authors: Iino
authors: S
authors: S
authors: Ozawa
mesh_terms: D015763:2-Amino-5-phosphonovalerate; D000818:Animals; D002478:Cells, Cultured; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007473:Ion Channels / Q000187:drug effects*; D008274:Magnesium / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology*; D017378:Quinolinic Acid; D011805:Quinolinic Acids / Q000494:pharmacology*; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D007473:Ion Channels; D011725:Pyridines; D011805:Quinolinic Acids; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D015763:2-Amino-5-phosphonovalerate; D017378:Quinolinic Acid; D014633:Valine; D008274:Magnesium