Excitability changes in C fibers of rat sciatic nerve following impulse activity.

Three phases in the oscillatory changes of both threshold and conduction velocity were identified following impulse activity in single C fibers of rat sciatic nerves. These after-oscillations, occurring after the refractory period, varied with the number and timing of preceding 'conditioning' impulses. The excitability changes differed both qualitatively and quantitatively among fibers, thus implying underlying variation among C fibers in the density and distribution of voltage-gated channels and ion pumps.