Fig. 7.

Elimination of Kv2, but not Kv1, channels led to significant prolongation of the duration of the action potential.A, Action potentials were recorded from mature neurons using the current-clamp mode of the patch-clamp amplifier. A steady level of current was injected to hold the neuronal membrane at approximately −80 mV. Impulses were elicited by a 2.5 msec depolarizing current pulse. Examples representing the “average” impulse recorded from control (left), +Kv1 Mutant (middle), and +Kv2 Mutant(right) neurons are presented. B,Histogram presenting the distributions of durations of the action potential recorded from control, +Kv1 Mutant, and+Kv2 Mutant neurons. All mature control neurons had impulse durations of <3 msec. Elimination of Kv2 channels shifted the distribution to much larger values than did suppression of Kv1 channels. The duration of the impulse is defined as the time between peak and half-repolarization. Inset, In one +Kv2 Mutant neuron, the action potential had an unusually long duration, and repolarization was not observed during the recording sweep. One neuron (*) fired an action potential with an unusually long duration, as shown in the inset (*).