Figure 1. Impairment of NMDA-dependent TTX-resistant oscillations.

Following whole-cell access, cells were dialyzed with either EGTA (5 mM) or BAPTA (5 mM) before induction of membrane potential oscillations in NMDA (50 µM), TTX (0.5 µM), glycine (1 µM), and strychnine (5 µM). A A ventral horn neuron was dialyzed for 30 minutes prior to NMDA application (black bar). After depolarization, the cell remained at a plateau for several minutes before the minimum amount of negative current necessary for repolarization was injected (bottom trace) and then held constant thereafter. Repetitive oscillations were either induced (EGTA, Ai top trace) or prevented (BAPTA, Aii middle trace). B EGTA (5 mM) perfusion immediately following whole-cell access prolongs the oscillation duration, necessitating increasing negative current injection (bottom trace) for repolarization. C In a neuron recorded in current clamp with a patch pipette containing EGTA (5 mM), block of K_Ca2 channels with UCL 1684 (100 nM) prevented NMDA receptor-induced oscillations, which recovered after washout.