Electrophysiological study on the antinociceptive effect of xenon.

Xenon(Xe)suppresses wide dynamic range(WDR)neurons in cat spinal cord to a similar extent as nitrous oxide(Nii D22齐埃D2O)。The antinociceptive action of N I D22文件D2O involves the descending inhibitory system。In order to clarify whether the descending inhibitory system is also involved in the antinociceptive action of Xe，we compared the effects of Xe on the spinal cord dorsal horn neurons with those of N I D22ⅡD2O in spinal cord transected cats anesthetized withα-chloralose and urethane。We investigated the change of WDR neuron responses to touch and pinch by both anesthetics.70%Xe significantly suppressed both touch-and pinch-evoked responses in all 12 neurons。In contrast，70%N I D22 ii D2O did not show significant suppression in both touch-and pinch-evoked responses.These results suggest that the antinociceptive action of Xe might not be mediated by the descending inhibitory system，but instead may be produced by direct effect on spinal dorsal horn neurons.

Xenon (Xe) suppresses wide dynamic range (WDR) neurons in cat spinal cord to a similar extent as nitrous oxide (NィイD22ィエD2O). The antinociceptive action of NィイD22ィエD2O involves the descending inhibitory system. In order to clarify whether the descending inhibitory system is also involved in the antinociceptive action of Xe, we compared the effects of Xe on the spinal cord dorsal horn neurons with those of NィイD22ィエD2O in spinal cord transected cats anesthetized with α-chloralose and urethane. We investigated the change of WDR neuron responses to touch and pinch by both anesthetics. 70% Xe significantly suppressed both touch-and pinch-evoked responses in all 12 neurons. In contrast, 70% NィイD22ィエD2O did not show significant suppression in both touch-and pinch-evoked responses. These results suggest that the antinociceptive action of Xe might not be mediated by the descending inhibitory system, but instead may be produced by direct effect on spinal dorsal horn neurons.