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- Title
Thiopental directly depresses lumbar dorsal horn neuronal responses to noxious mechanical stimulation in goats.
- Authors
Sudo, M.; Sudo, S.; Chen, X. G.; Piercy, M.; Carstens, E.; Antognini, J. F.
- Abstract
<bold>Background: </bold>Thiopental has hypnotic actions in the brain, but it also depresses nociceptive transmission. In this study we examined whether thiopental had direct (spinal) and/or indirect (supraspinal) effects on the responses of single lumbar dorsal horn neurons to noxious mechanical stimulation, using a method to deliver thiopental differentially to either the torso or cranial circulation in goats.<bold>Methods: </bold>Goats (n=10) were anesthetized with isoflurane and neck dissections performed to permit cranial bypass. A lumbar laminectomy was made to permit single-unit recording of lumbar dorsal horn neuronal activity (1-2 neurons/animal). Isoflurane was maintained at 0.8+/-0.1% to both head and torso throughout the study. During cranial bypass, thiopental was separately administered to the torso (low dose, 1.5+/-0.5 mg/kg; high dose, 3.7+/-0.5 mg/kg) or cranial (low dose, 0.12+/-0.03 mg/kg; high dose, 0.2 mg/kg) circulation.<bold>Results: </bold>Thiopental administered to the torso significantly depressed dorsal horn neuronal responses to noxious stimulation at the high dose: 757+/-471 to 392+/-305 impulses/min at 1 min post-injection, P<0.006 (n=14); evoked responses recovered at 5 min post-injection. At the low dose, there was a similar numerical decrease, but this did not reach significance: 876+/-780 to 407+/-499 impulses/min at 1 min post-injection, P>0.05 (n=6). No significant change was observed when thiopental was administered to the cranial circulation: low dose, 1061+/-1167 to 965+/-874 impulses/min at 1 min post-injection, P>0.05 (n=10); high dose, 864+/-331 to 917+/-525 impulses/min at 1 min post-injection, P>0.05 (n=8).<bold>Conclusion: </bold>Thiopental has a direct (spinal) depressant effect on dorsal neuronal responses to noxious stimulus, but no significant supraspinal effect.
- Subjects
BARBITURATES; NEURAL stimulation; ANALGESIA; HYPERALGESIA; PHYSIOLOGY
- Publication
Acta Anaesthesiologica Scandinavica, 2001, Vol 45, Issue 7, p823
- ISSN
0001-5172
- Publication type
journal article
- DOI
10.1034/j.1399-6576.2001.045007823.x