Figure 5. Electrically evoked action potentials are not blocked by cobalt.

A, somal action potential activity following a current stimulus delivered to the carotid body. Each sweep is an average of 20 trials and is shown with increasing stimulus intensity. Stimulus artefact is apparent near 0.4 ms, and the evoked action potential is apparent near 5-6 ms. Addition of cobalt slowed the conduction time from 5.05 to 5.85 ms. B, the ordinate is the percentage of successfully evoked spikes based on the average, post-stimulus potential change for one preparation. Cobalt (▵) increased the stimulus threshold compared with control (○), but did not block the evoked spike.