NMDA receptors at excitatory synapses in the hippocampus: test of a theory of magnesium block.
Excitatory postsynaptic currents (EPSCs) were studied using the whole-cell patch-clamp technique to record from rat hippocampal pyramidal neurons in both slices and dissociated cultures. The voltage- and magnesium-dependence of the N-methyl-D-aspartate (NMDA) component of the EPSCs was quantified by measuring the amplitude of this component at a range of holding potentials (-80 mV to 60 or 80 mV) in several bath magnesium concentrations (0.2 microM, 0.1, 1 and 10 mM). All of our results were well-fitted by a theory of magnesium block developed from single-channel studies of extrajunctional NMDA channels in culture. It is concluded that extrasynaptic and subsynaptic NMDA channels both in culture and in situ have identical properties of magnesium block.
Bekkers
J M
JM
Salk Institute, Howard Hughes Medical Institute, La Jolla, CA 92037.
Stevens
C F
CF
D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity / Q000187:drug effects; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D006624:Hippocampus / Q000502:physiology*; D008274:Magnesium / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011712:Pyramidal Tracts / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D016194:Receptors, N-Methyl-D-Aspartate; D008274:Magnesium