When tail tips of the Japanese newt (Cynops pyrrhogaster pyrrhogaster) were amputated, large ionic currents were detected around the stump using a vibrating probe system. The initial wound currents flowed outwardly through the whole stump, and then localized within 24 hr toward the central region of the stump. Current densities reached a peak of about 450 μA • cm−2 (about 900 times greater than before amputation) within one half of a day after amputation, and returned to levels similar to the intact tail tip by 4 days, i.e., the wound currents were transient. The swelling of the stump end (regenerate or blastema) occurred about 7 days after amputation. The major ion carrying the currents is thought to be Na , because the currents were strongly inhibited by 0.5 mM ouabain added in the external medium or by Na -deficient medium. These findings are consistent with those of newt limb stump.
