Bioelectricity and regeneration. I. Initiation of frog limb regeneration by minute currents

Abstract

Abstract We have applied 0.2 μamps of current to the forelimb stump of Rana adults for several weeks. The stimulator was designed to avoid introduction of any physiologically active electrode products into the tissue. Current was applied to the dorsal postaxial region of the stump. Cathodal (i.e., distally negative) current initiated partial regeneration; anodal (i.e., distally positive) current initiated extensive destruction of the limb; while implantation of sham stimulators (delivering no current) yielded limbs showing just a healing response. Regeneration was indicated by organized extension of the severed radio‐ulna, newly formed muscle, ligament, and isolated cartilage rods that were partially segmented. Moreover, extraordinarily large amounts of nerve developed in the regenerated tissue. We conclude that the cathodally initiated regeneration was mediated by small electrical fields within the stump and not by electrode products. However, an electrode product (Ag + ion) cannot be completely excluded as a possible mediator of anodal destruction.