[Field potentials evoked by stimulation of DLF in the rat spinal cord]

When stimulation of DLF at cervical cord, a train of evoked potentials are recorded with a microelectrode at lumber level in rat. The longer slow positive potential wave, latency 7.22 +/- 1.41 ms, peak time 15 +/ 12 +/- 5.58 ms, duration 93 +/ 92 +/- 9.06 ms, is called DLF-FP. The negative center of the isopotential map of DLF-FP is located at 1.0-1.3 mm below the dorsal surface nearly in coincidence with that of the P1-FP evoked by the sural nerve stimulation. The amplitude of DLF-FP was decreased by picrotoxin and increased by strychnine. Both summation and inhibition can be observed between the potentials evoked by stimulation of the sural nerve and DLF. The results mentioned above show that DLF-FP is the reflection of primary afferent depolarization probably by the same spinal circuit underlying P1-FP.