Effects of transcutaneous electrical nerve stimulation (TENS) on spontaneous and noxiously evoked dorsal horn cell activity in cats with transected spinal cords

Effects of transcutaneous electrical nerve stimulation (TENS) on spontaneous and noxiously evoked dorsal horn neurons were studied in alpha-chloralose anesthetized cats after spinal cords had been transected at the T12 segment. Previous work in cats with intact cords showed that TENS applications to somatic receptive fields could significantly reduce and maintain decreased dorsal horn cell activity. The purpose of this study was to determine if supraspinal mechanisms were involved with the initial reduction of dorsal horn cell activity during TENS applications. Extracellular action potentials of dorsal horn neurons were recorded in the absence of supraspinal influences. The results demonstrated that spontaneously and noxiously evoked cell activities were reduced significantly during TENS and no significant difference was found between pre-TENS control activity and post-TENS application cell activity. This information implies that initial gating (reduction in cell activity), which occurs during TENS applications, is due to a segmental effect.