Increasing isoflurane from 0.9 to 1.1 minimum alveolar concentration minimally affects dorsal horn cell responses to noxious stimulation

Joseph F. Antognini, Earl Carstens

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

Background: The spinal cord appears to be the site at which isoflurane suppresses movement that occurs in response to a noxious stimulus. In an attempt to localize its site of suppressant action, the authors determined the effect of isoflurane on dorsal horn neuronal responses to supramaximal noxious stimulation at end-tidal concentrations that just permitted and just prevented movement. Methods: Rats (n = 14) were anesthetized with isoflurane, and after lumbar laminectomy, the minimum alveolar concentration (MAC) for each rat was determined using a supramaximal mechanical stimulus. In these same rats, after extracellular microclectrode placement in the lumbar spinal cord, dorsal horn neuronal responses to the supramaximal stimulus were determined at the concentrations of isoflurane that bracketed each rat's MAC (0.1% higher and lower than MAC). The MAC of isoflurane was then re-determined. Results: Dorsal horn neuronal response was 1,757 ± 892 impulses/min at 0.9 MAC and 1,508 ± 988 impulses/min at 1.1 MAC, a 14% decrease (P < 0.05). Cell responses varied, with some cells increasing their response at the higher concentration of isoflurane. The MAC of isoflurane was 1.38 ± 0.2% before and 1.34 ± 0.2% after determination of dorsal horn neuronal responses. Conclusions: Isoflurane, at concentrations that bracket MAC, has a variable and minimal depressant effect on dorsal horn cell responses to noxious mechanical stimulation. These data suggest that the major action of isoflurane to suppress movement evoked by a noxious stimulus might occur primarily at a site other than the dorsal horn.

Original languageEnglish (US)
Pages (from-to)208-214
Number of pages7
JournalAnesthesiology
Volume90
Issue number1
StatePublished - Jan 1999

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Posterior Horn Cells
Isoflurane
Spinal Cord
Laminectomy
Spinal Cord Dorsal Horn

Keywords

  • Anesthetic requirements
  • Pain

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

Cite this

Increasing isoflurane from 0.9 to 1.1 minimum alveolar concentration minimally affects dorsal horn cell responses to noxious stimulation. / Antognini, Joseph F.; Carstens, Earl.

In: Anesthesiology, Vol. 90, No. 1, 01.1999, p. 208-214.

Research output: Contribution to journalArticle

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