Jm. Bekkers et Cf. Stevens, NMDA RECEPTORS AT EXCITATORY SYNAPSES IN THE HIPPOCAMPUS - TEST OF A THEORY OF MAGNESIUM BLOCK, Neuroscience letters, 156(1-2), 1993, pp. 73-77
Excitatory postsynaptic currents (EPSCs) were studied using the whole-
cell patch-clamp technique to record from rat hippocampal pyramidal ne
urons in both slices and dissociated cultures. The voltage- and magnes
ium-dependence of the N-methyl-D-aspartate (NMDA) component of the EPS
Cs was quantified by measuring the amplitude of this component at a ra
nge of holding potentials (-80 mV to 60 or 80 mV) in several bath magn
esium concentrations (0.2muM, 0.1, 1 and 10 mM). All of our results we
re well-fitted by a theory of magnesium block developed from single-ch
annel studies of extrajunctional NMDA channels in culture. It is concl
uded that extrasynaptic and subsynaptic NMDA channels both in culture
and in situ have identical properties of magnesium block.