The effect of pentobarbital sodium on the dorsal horn of the spinal cord.

The effect of intravenously administered pentobarbital sodium on the activity of single unit in Rexed lamina V of the transected feline lumbar spinal cord was studied using an extracellular microelectrode recording technique. Pentobarbital sodium 1.0 mg·kg(-1), 2.5 mg·kg(-1), and 5.0 mg·kg(-1) administered intravenously suppressed both the spontaneous and the evoked activity in Rexed lamina V cells, known to respond principally to noxious stimuli, in a dose-dependent manner. The maximum depression of cell activity occurred within 5 min after intravenous administration. The recovery of cell activity occurred within 70 min after intravenous administration of pentobarbital sodium. We conclude that pentobarbital sodium intravenously administered has a suppressive effect on single unit activity of cells in Rexed lamina V and probably has an analgesic effect. Its suppressive effect is dose-dependent.