Intrathecal picrotoxin minimally alters electroencephalographic responses to noxious stimulation during halothane and isoflurane anesthesia

C. L. Dominguez, Linda S Barter, Joseph F. Antognini

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Background: Isoflurane and halothane act in the spinal cord to blunt ascending transmission of impulses to the brain resulting from noxious stimulation. Because intrathecal picrotoxin (an antagonist at the gamma-aminobutyric acid-A receptor) partially reverses the immobilizing effect of isoflurane and halothane, we hypothesized that the electroencephalographic response to noxious stimulation would likewise be partially reversed by intrathecal picrotoxin. Methods: Rats were anesthetized with isoflurane (n = 8) or halothane (n = 8) and a laminectomy performed. Following determination of minimum alveolar concentration (MAC), the electroencephalogram (EEG) was recorded during separate applications of a hindpaw clamp, tail clamp and electrical current to the tail at 0.8 and 1.2 MAC. Picrotoxin was then applied to the exposed spinal cord and the EEG response to noxious stimulation again determined. Results: The EEG was more active during halothane anesthesia than isoflurane (spectral edge frequency for 95% power: 25.6 ± 2.1 Hz vs. 23.1 ± 1.6 Hz, P < 0.05). Noxious stimulation usually caused the EEG to shift to higher frequencies (e.g. for 0.8 MAC halothane, median edge frequency for 50% power: from 7.6 ± 3.1 Hz to 10.7 ± 2.6 Hz, P < 0.05). Picrotoxin minimally affected this response. Conclusions: Noxious stimulation evokes an EEG response that is minimally altered by intrathecal picrotoxin. This suggests that isoflurane and halothane do not have GABAergic actions in the spinal cord that indirectly suppress the EEG response.

Original languageEnglish (US)
Pages (from-to)763-770
Number of pages8
JournalActa Anaesthesiologica Scandinavica
Volume49
Issue number6
DOIs
StatePublished - Jul 2005

Keywords

  • Electroencephalography
  • Halothane
  • Isoflurane
  • Picrotoxin

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

Fingerprint Dive into the research topics of 'Intrathecal picrotoxin minimally alters electroencephalographic responses to noxious stimulation during halothane and isoflurane anesthesia'. Together they form a unique fingerprint.

  • Cite this