Figure 2. Cs⁺-mediated inhibition of the DAP is not voltage dependent.

A, chart recording of membrane voltage (upper trace) showing the effects of 3 mM Cs⁺ (bar) on DAPs following trains of 4 action potentials triggered by depolarizing current pulses (upward deflections in lower trace). In this experiment a variable amount of inward current (lower trace) was injected into the cell to maintain a constant initial potential (−57 mV) during exposure to Cs⁺. The traces in B are excerpts of the recording shown in A. Note that compared with control (a), addition of Cs⁺ first inhibited the after-discharge (b) and then caused a further decrease in the amplitude of the DAP (c). The effects were reversible upon washout of Cs⁺ (d). Full spike amplitude not shown.