Fig. 7.

Catechol broadened spikes and slightly inhibited repetitive firing. A, In current-clamp recordings from a dissociated neuron a brief outward current pulse triggered a spike (bottom traces, voltage). One hundred micromolar and 1 mm catechol progressively slowed the repolarizing phase, broadening the spike compared with control. B, Repetitive firing of a cell that was depolarized by 80 pA to elicit a train of spikes in control saline. Ten micromolar and 100 μm catechol reduced the average frequency of firing and thus the number of spikes during the pulse. In this cell the initial frequency was also slightly reduced, but across all cells the change was not significant. Similar results were seen in cells that exhibited stronger accommodation.