The depressant effect of halothane and sodium thiopental on the spontaneous and evoked activity of dorsal horn cells: lamina specificity, time course and dose dependence.
The effects of halothane and sodium thiopental on dorsal horn cell unit activity were studied in the lumbar spinal cord of decerebrate, low thoracic spinal cats. Both halothane (0.5, 1 and 1.5%) and sodium thiopental (2.5, 5 and 10 mg/kg) depressed, in a dose-dependent manner, the spontaneous firing frequency of cells in Rexed laminae I, V and VI and the evoked firing frequency of cells in laminae I and V. They, however, had no effect on cells in lamina IV. The maximum depression of cell activity occurred 5 to 8 minutes after inhalation of halothane and 2 to 3 minutes after the intravenous administration of sodium thiopental. The recovery of cell activity occurred within 15 to 30 minutes after discontinuation of halothane and within 10 to 30 minutes after intravenous administration of sodium thiopental. The depressive effect of halothane and sodium thiopental, both primarily hypnotic anesthetics, on lamina VI cells is in contrast to our previous finding that morphine sulfate, nitrous oxide and ketamine hydrochloride, primarily analgesic agents, had no significant effect on this lamina.
D000818:Animals; D002415:Cats; D003655:Decerebrate State; D003864:Depression, Chemical; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D006221:Halothane / Q000494:pharmacology*; D008297:Male; D013116:Spinal Cord / Q000187:drug effects* / Q000502:physiology; D013126:Spinal Nerve Roots / Q000187:drug effects / Q000502:physiology; D013874:Thiopental / Q000494:pharmacology*; D013997:Time Factors
D013874:Thiopental; D006221:Halothane