Glutamate-induced currents in acutely dissociated guinea pig locus coeruleus neurons

To investigate the properties of L-glutamate (Glu) receptors in single locus coeruleus (LC) neurons at mature stage, we recorded the Glu-induced currents in the LC neurons acutely dissociated from adult guinea pigs, using the whole-cell patch-clamp technique. The concentration-current relationships show that Glu-induced currents in LC neurons might be predominantly mediated by non-NMDA receptors rather than NMDA receptors. The current-voltage relationship of NMDA or non-NMDA receptor-mediated currents indicated that both subtypes of the Glu-receptors operate non-selective cation channels, and that the NMDA receptor-operated channels but not the non-NMDA receptor-operated channels are permeable to Ca2+. These results suggest that in LC neurons, the normal excitatory neurotransmission may be mediated through non-NMDA receptors, and that NMDA receptors may be involved in intracellular signal transduction by their Ca2+ permeability.