Electrical stimulation of nerve regeneration in the rat: the early effects evaluated by a vibrating probe and electron microscopy.

This study examines the effect of applied d.c. electric fields on nerve regeneration following injury to the rat sciatic nerve using the circularly vibrating probe and electron microscopy. The transected and treated nerve which received a d.c. electrical stimulator (0.6 mu A) was compared with untreated transected and crushed nerves. At one week postoperative, the probe was used to measure in vivo the current density along the nerve length. All nerves studied had a proximal peak at the lesion site and a second peak at varying distal locations: crushed/untreated (13.3 mm), transected/untreated (9.7 mm) and transected/treated (16.3 mm). A significant difference (69%) between the distal peak distances in the two transection groups suggests that the electrical treatment enhanced the progress of nerve regeneration. There were no significant differences between the mean peak amplitudes (1.6-2.2 mu A/cm2). Applied verapamil reduced the peaks, suggesting they are associated in part with a calcium-dependent current. Electron microscopy at selected nerve regions indicated that the peaks correspond to regenerating axonal growth cones. The results suggest the potential clinical application of d.c. electric fields in the treatment of nerve injuries.