Fig. 1. Cholinergic nicotinic actions on cardiac parasympathetic neurons. Nicotine evokes an inward current in these neurons (A ). Nicotine also elicits an increase in the frequency of miniature glutamatergic synaptic events (minis) (B ) and an increase in mini amplitude (C ). After a 20-min delay, nicotine was reapplied to the cardiac parasympathetic neuron, but now in the presence of ketamine. Administration of ketamine (10 μm) significantly inhibited the nicotine-evoked inward current (D ) and increase in mini frequency (E ) but did not significantly alter the nicotine-evoked increase in mini amplitude (F ).