Evidence for two types of potassium channel in human motor axons in vivo.

We have obtained evidence that human axons in vivo possess potassium channels similar to two types found in rat nerve, giving rise to a slowly activating potassium conductance and inward rectification. This was achieved non-invasively by tracking the thresholds of single motor axons in the forearm while applying polarizing currents. On average, human ulnar motor axons appear to have fewer outwardly rectifying potassium channels than rat nerves.