Differential effects of halothane and isoflurane on lumbar dorsal horn neuronal windup and excitability

J. M. Cuellar, R. C. Dutton, J. F. Antognini, Earl Carstens

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Background. Windup of spinal nociceptive neurones may underlie temporal summation of pain, influencing the minimum alveolar concentration (MAC) of anaesthetics required to prevent movement to supramaximal stimuli. We hypothesized that halothane and isoflurane would differentially affect windup of dorsal horn neurones. Methods. We recorded 18 nociceptive dorsal horn neurones exhibiting windup to 1 Hz electrical hindpaw stimuli in rats. Effects of 0.8 and 1.2 MAC isoflurane and halothane were recorded in the same neurones (counterbalanced, crossover design). Windup was calculated as the total number of C-fibre (100-400 ms latency) plus afterdischarge (400-1000 ms latency) spikes/20 stimuli (area under curve, AUC) or absolute windup (C-fibre plus afterdischarge-20×initial response). Results. Increasing isoflurane from 0.8 to 1.2 MAC did not affect AUC, but increased absolute windup from 429 (62) to 618 (84) impulses/20 stimuli (P<0.05) and depressed the initial C-fibre response from 14 (3) to 8 (2) impulses (P<0.05). Increasing halothane from 0.8 to 1.2 MAC depressed AUC from 690 (79) to 537 (65) impulses/20 stimuli (P<0.05) and the initial response from 18 (2) to 13 (2) impulses (P<0.05), but absolute windup was not affected. Absolute windup was 117% greater during 1.2 MAC isoflurane compared with 1.2 MAC halothane. Conclusions. Windup was significantly greater under isoflurane than halothane anaesthesia at 1.2 MAC, whereas the initial C-fibre response was suppressed more by isoflurane. These findings suggest that these two anaesthetics have mechanistically distinct effects on neuronal windup and excitability.

Original languageEnglish (US)
Pages (from-to)617-625
Number of pages9
JournalBritish Journal of Anaesthesia
Volume94
Issue number5
DOIs
StatePublished - May 2005

Fingerprint

Isoflurane
Halothane
Unmyelinated Nerve Fibers
Area Under Curve
Posterior Horn Cells
Nociceptors
Anesthetics
Cross-Over Studies
Spinal Cord Dorsal Horn
Anesthesia
Neurons
Pain

Keywords

  • Anaesthetics volatile, halothane
  • Anaesthetics volatile, isoflurance
  • Model, rat, spinal cord
  • Pain
  • Windup

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

Cite this

Differential effects of halothane and isoflurane on lumbar dorsal horn neuronal windup and excitability. / Cuellar, J. M.; Dutton, R. C.; Antognini, J. F.; Carstens, Earl.

In: British Journal of Anaesthesia, Vol. 94, No. 5, 05.2005, p. 617-625.

Research output: Contribution to journalArticle

Cuellar, J. M. ; Dutton, R. C. ; Antognini, J. F. ; Carstens, Earl. / Differential effects of halothane and isoflurane on lumbar dorsal horn neuronal windup and excitability. In: British Journal of Anaesthesia. 2005 ; Vol. 94, No. 5. pp. 617-625.
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abstract = "Background. Windup of spinal nociceptive neurones may underlie temporal summation of pain, influencing the minimum alveolar concentration (MAC) of anaesthetics required to prevent movement to supramaximal stimuli. We hypothesized that halothane and isoflurane would differentially affect windup of dorsal horn neurones. Methods. We recorded 18 nociceptive dorsal horn neurones exhibiting windup to 1 Hz electrical hindpaw stimuli in rats. Effects of 0.8 and 1.2 MAC isoflurane and halothane were recorded in the same neurones (counterbalanced, crossover design). Windup was calculated as the total number of C-fibre (100-400 ms latency) plus afterdischarge (400-1000 ms latency) spikes/20 stimuli (area under curve, AUC) or absolute windup (C-fibre plus afterdischarge-20×initial response). Results. Increasing isoflurane from 0.8 to 1.2 MAC did not affect AUC, but increased absolute windup from 429 (62) to 618 (84) impulses/20 stimuli (P<0.05) and depressed the initial C-fibre response from 14 (3) to 8 (2) impulses (P<0.05). Increasing halothane from 0.8 to 1.2 MAC depressed AUC from 690 (79) to 537 (65) impulses/20 stimuli (P<0.05) and the initial response from 18 (2) to 13 (2) impulses (P<0.05), but absolute windup was not affected. Absolute windup was 117{\%} greater during 1.2 MAC isoflurane compared with 1.2 MAC halothane. Conclusions. Windup was significantly greater under isoflurane than halothane anaesthesia at 1.2 MAC, whereas the initial C-fibre response was suppressed more by isoflurane. These findings suggest that these two anaesthetics have mechanistically distinct effects on neuronal windup and excitability.",
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AU - Antognini, J. F.

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