Purpose: We tested the hypothesis that propofol, acting in the brain, would either enhance, or have no effect, on lumbar dorsal horn neuronal responses to a noxious mechanical stimulus applied to the hindlimb. We recorded the response of lumbar dorsal horn neurons during differential delivery of propofol to the brain and torso of goats. Methods: Goats were anesthetized with isoflurane and neck dissections performed which permitted cranial bypass. A laminectomy was made to allow microelectrode recording of lumbar dorsal horn neuronal activity. Isoflurane was maintained at 0.8 ± 0.1% to both head and torso throughout the study. During cranial bypass propofol was separately administered to the torso (1 mg.kg-1, n=7; 3.75 mg.kg-1, n=8) or cranial (0.04 mg.kg-1, n=7; 0.14 mg.kg-1, n=8) circulations. Results: Propofol administered to the torso depressed dorsal horn neuronal responses to noxious stimulation: low dose: 500 ± 243 to 174 ± 240 impulses.min-1 at one minute post-injection, P < 0.001; high dose: 478 ± 204 to 91 ± 138 impulses.min-1 at one minute post-injection, P < 0.05). Propofol administered to the cranial circulation had no effect: low dose: 315 ± 150 to 410 ± 272 impulses.min-1, P > 0.05; high dose: 462 ± 261 to 371 ± 196 impulses.min-1, P > 0.05. Conclusions: These data indicate that propofol has a direct depressant effect on dorsal horn neuronal responses to noxious stimulation, with little or no indirect supraspinal effect.
|Original language||English (US)|
|Number of pages||7|
|Journal||Canadian Journal of Anesthesia|
|State||Published - 2000|
ASJC Scopus subject areas
- Anesthesiology and Pain Medicine