Whole-cell voltage-clamped currents were recorded using low resistance patch electrodes containing K+ channel blockers with the local anaesthetic QX-314 (20mM). Under these conditions voltage-gated Na+ conductances and regenerative spiking activity were blocked, leaving Ca2+ conductances. The effect of QX-314 resembled that of extracellular tetrodotoxin but had the advantage of being localised to one cell therefore permitting recording of synaptic currents. Excitatory synaptic current recordings were progressively improved over the first 25 minutes of recording as input resistance increased. After this time postsynaptic currents were stable for at least 1 h.