THE EFFECT OF XENON ON SPINAL DORSAL HORN NEURONS - A COMPARISON WITHNITROUS-OXIDE

We compared the effects of xenon (Xe) on the spinal cord dorsal horn n eurons with those of nitrous oxide (N2O) in cats anesthetized with chr olarose and urethane. We assessed the potency of both anesthetics by t he inhibition of wide dynamic range neuron responses evoked by cutaneo us noxious (pinch) stimulation to a hindpaw. During 70% Xe inhalation, the responses of 7 of 11 neurons to pinch stimulation were suppressed . N2O, 70%, suppressed it in 8 of 11 neurons. The potency of Xe and N2 O was compared in six neurons that were suppressed by both anesthetics . After 20 min of Xe inhalation, the response to pinch was suppressed to 49.5% +/- 8.2% (mean +/- SE) while N2O, 70% in oxygen, suppressed i t to 45.9% +/- 7.9%. The difference between N2O and Xe was not signifi cant. We conclude that Xe and N2O suppress the spinal cord dorsal horn neurons to a similar degree.