Voltage sensitivity of NMDA-receptor mediated postsynaptic currents.
Patch-clamp techniques were used to record pharmacologically-isolated N-methyl-D-aspartate-mediated excitatory postsynaptic currents (NMDA-EPSCs) from dentate granule cells in thin rat hippocampal slices. Membrane voltage modulated these EPSCs in two ways. Firstly, depolarization from resting potential enhanced EPSC amplitudes, as expected for a voltage-dependent block by Mg2+ of synaptically activated NMDA receptor channels. Secondly, depolarization markedly prolonged the time course of decay of NMDA-EPSCs in normal and low extracellular Mg2+. Both mechanisms were complementary in establishing a strong dependence between membrane potential and the amount of charge, namely Ca2+, transferred through synaptically activated NMDA receptor channels, that presumably underlies induction of long-term potentiation in the hippocampus.
Konnerth
A
A
Zelluläre Neurophysiologie, Max-Planck-Institut für biophysikalische Chemie, Göttingen, Federal Republic of Germany.
Keller
B U
BU
Ballanyi
K
K
Yaari
Y
Y
D000818:Animals; D002118:Calcium / Q000502:physiology; D004594:Electrophysiology; D006624:Hippocampus / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D008274:Magnesium / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000502:physiology*; D013569:Synapses / Q000502:physiology*
D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D008274:Magnesium; D002118:Calcium