Figure 1. Current clamp recordings from Purkinje neurons in cerebellar slices demonstrate both Na⁺ and Ca²⁺ action potentials.

Right-hand traces are at expanded time scales. A, under control conditions, injection of 0.5 nA depolarizing current through the recording pipette evoked bursts of Na⁺ spikes (arrows) interrupted by single Ca²⁺ spikes (▵). B, when TTX was added to the bath solution, the same cell fired only Ca²⁺ spikes. Each spike was followed by a deep after-hyperpolarization (AHP). C, recordings from a different cell demonstrate Na⁺ spikes in the absence of Ca²⁺ spikes due to the block of Ca²⁺ channels with 100 μm bath-applied cadmium chloride.