Abstract Following peripheral nerve section, the cell body and proximal axon undergo various physiological and morphological changes which may be associated with regrowth. We found that axotomy reduced the amplitude and duration of the afterhyperpolarization (AHP) of the action potential (AP) of bullfrog sympathetic neurones. In addition, the repolarization of the AP was slowed. The Ca 2+-channel blocker, Cd 2+ (200 μM) produced similar effects in normal cells by blocking the Ca 2+-sensitive K + conductances (g k, Ca) which contribute to the AHP and to AP repolarization. Although Ca 2+-channel function was preserved after axotomy, Cd 2+ did not affect axotomized neurones. This suggests that axotomy promotes a functional loss of g k, Ca which could reflect a regenerative response of the cell to injury.