Kinetics and Mg2+ block of N-methyl-D-aspartate receptor channels during postnatal development of hippocampal CA3 pyramidal neurons

Neuroscience. 1995 Dec;69(4):1057-65. doi: 10.1016/0306-4522(95)00337-i.


Voltage-dependent magnesium block of N-methyl-D-aspartate-activated channels, and the N-methyl-D-aspartate component of excitatory synaptic currents were studied in CA3 pyramidal neurons of hippocampal slices from immature (postnatal day 3-8) and adult (postnatal day 25-60) rats. In all neurons studied the kinetics of single-channel openings in cell-attached and inside-out configurations was strongly modulated by extracellular Mg2+, in a voltage-dependent manner. No age-dependent difference in the Mg2+ sensitivity of N-methyl-D-aspartate channels was observed. At physiological concentrations of external Mg2+ (1.3 mM), N-methyl-D-aspartate components of excitatory synaptic currents measured from immature and adult rats displayed a similar voltage-dependence. In immature neurons (postnatal day 3-6), the N-methyl-D-aspartate component of excitatory postsynaptic currents decay time-course was a single-exponential with an average time-constant of about 300 ms. In neurons from older animals the decay was described by a double-exponential function with both a fast component (tau f, 54-130 ms) and a slow component (tau s, 275-400 ms). With age, the contribution of the fast component increased and the decay time-course of the N-methyl-D-aspartate component of excitatory postsynaptic currents accelerated. It is concluded that the Mg2+ block of N-methyl-D-aspartate channels in CA3 pyramidal neurons does not change with development, but the kinetic properties of N-methyl-D-aspartate receptor channels are developmentally regulated.

MeSH terms

  • Age Factors
  • Animals
  • Hippocampus / drug effects*
  • Kinetics
  • Magnesium / pharmacology*
  • Male
  • Membrane Potentials / drug effects*
  • Patch-Clamp Techniques
  • Pyramidal Cells / drug effects*
  • Rats
  • Rats, Wistar
  • Receptors, N-Methyl-D-Aspartate / drug effects*


  • Receptors, N-Methyl-D-Aspartate
  • Magnesium