Evidence for a magnesium-insensitive membrane resistance increase during NMDA-induced depolarizations in rat neocortical neurons in vitro.
The responses of rat neocortical neurons in vitro to iontophoretically applied N-methyl-D-aspartate (NMDA) were investigated by means of intracellular recording in the presence and absence of extracellular magnesium ions (Mg2+). At Mg2+-concentrations of 1.3 mM the neurons responded with a depolarization accompanied by an increase in membrane resistance. Upon removal of Mg2+ the NMDA-induced depolarization was markedly potentiated. However, even in neurons recorded from slices which were incubated in a Mg2+-free solution for 3-7 h, the NMDA response was still associated with a resistance increase, suggesting that the voltage-dependence of the NMDA-activated conductance is not exclusively determined by Mg2+.
D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects*; D004553:Electric Conductivity; D005625:Frontal Lobe / Q000187:drug effects*; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D007473:Ion Channels / Q000187:drug effects*; D008274:Magnesium / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D016202:N-Methylaspartate; D010069:Oxadiazoles / Q000494:pharmacology; D016318:Quisqualic Acid; D051381:Rats; D011919:Rats, Inbred Strains
D005971:Glutamates; D007473:Ion Channels; D010069:Oxadiazoles; D001224:Aspartic Acid; D018698:Glutamic Acid; D016202:N-Methylaspartate; D016318:Quisqualic Acid; D008274:Magnesium