THE NMDA RECEPTOR CONTRIBUTES TO ANOXIC AGLYCEMIC INDUCED IRREVERSIBLE INHIBITION OF SYNAPTIC TRANSMISSION

Percent recovery of CA1 field EPSP amplitude following various anoxic aglycemic (AA) periods was examined in rat hippocampal slices superfused with MK-801 (0.1 muM, 1 muM, 10 muM) or Mg2+-free artificial cerebrospinal fluid. Slices treated with 0.1 muM MK-801 showed greater percent recuperation of EPSP amplitude following 3 min 30 s of AA (36 +/- 12% vs 6 +/- 4% in controls). Higher concentrations of MK-801 resulted in a greater recovery of EPSP amplitudes in more than one time period of AA, with 10 muM MK-801 providing protection in up to 4 min 30 s AA. Percent recuperation of EPSP amplitude was smaller in Mg2+-free slices following 2 min (34 +/- 15% vs 81 +/- 11% in controls) and 2 min 30 (25 +/- 14% vs 77 +/- 10% in controls) of AA. These results suggest that the activation of the N-methyl-D-aspartate (NMDA) receptor channel may contribute to irreversible AA induced synaptic failure in CA1.