Suppressive action of enflurane on dorsal horn neurons in rabbits.

The neurophysiologic mechanism of the suppressive action of enflurane on spinal nociceptive transmission was examined in rabbits with intact and with transected spinal cords. Enflurane suppressed nociceptive responses in both intact and transected spinal cord groups. The suppressive effects of enflurane were significantly greater in the intact group than in the transected group. The suppressive effects of enflurane were not reversed by the addition of 0.2 mg·kg of naloxone. These results suggest that enflurane suppresses nociceptive responses by activating descending inhibitory systems and directly suppressing activity at the spinal level. This suppressive action of enflurane does not interact with the opioid receptor.