A, a single vagotomized NGN displayed a DAP elicited by a train of 1 nA pulses 3 ms in duration delivered at 20 Hz. B, the substitution of 2.2 mm magnesium for calcium in the Locke solution almost completely blocked the DAP. C, a partial recovery of the DAP occurred when 2.2 mm barium was substituted for magnesium. D, switching to a normal (calcium-containing) Locke solution with 100 μm cadmium blocked the DAP again. E, a 2 min wash with normal Locke solution resulted in DAP recovery. All recordings from the same NGN. The horizontal dotted line represents the preset membrane potential, −70 mV.