Excitatory postsynaptic potentials in neonatal rat sympathetic preganglionic neurons: possible mediation by NMDA receptors.

Excitatory postsynaptic potentials (EPSPs) evoked in antidromically identified sympathetic preganglionic neurons (SPNs) and membrane depolarizations induced by N-methyl-D-aspartate (NMDA) applied by pressure ejection were increased by removing Mg ions from the perfusing media and blocked by D-2-amino-5-phosphonovalerate (APV), DL-APV and ketamine. Further, the amplitude of EPSPs and NMDA-induced depolarizations were decreased and increased by membrane hyperpolarization in Krebs solution with and without Mg2+, respectively. These findings indicate that the excitatory amino acid receptor mediating the EPSPs in SPNs may be of the NMDA subtype.