Immobilizing doses of halothane, isoflurane or propofol, do not preferentially depress noxious heat-evoked responses of rat lumbar dorsal horn neurons with ascending projections

Linda S Barter, Laurie O. Mark, Steven L. Jinks, Earl Carstens, Joseph F. Antognini

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15 Citations (Scopus)

Abstract

BACKGROUND: The spinal cord is an important site where volatile anesthetics decrease sensation and produce immobility. Beyond this knowledge, our understanding of a site of anesthetic action is limited. Previous evidence suggests that dorsal horn neurons with ascending projections may be more susceptible to depression by general anesthetics than local spinal interneurons. In this study we evaluated the effects of volatile and injectable general anesthetics on lumbar dorsal horn neurons with and without ascending projections. METHODS: Thirty-seven adult male rats underwent laminectomies at C1, for placement of a stimulating electrode, and T13/L1, for extracellular recording from the spinal cord dorsal horn. Neuronal responses to heat were evaluated under two doses of halothane, isoflurane, or propofol anesthesia. RESULTS: Under both halothane and isoflurane anesthesia, increasing the dose from 0.8 to 1.2 minimum alveolar concentration (MAC) had no significant effect on heat-evoked responses in neurons that had ascending projections identified via antidromic stimulation (AD) or those without ascending projections (nAD). Heat responses in AD neurons 1 min after IV administration of 3 and 5 mg/kg of propofol were reduced to 60% ± 18% (mean ± se) and 39% ± 14% of control respectively. Similarly, in nAD neurons responses were reduced to 56% ± 14% and 50% ± 10% of control by 3 and 5 mg/kg propofol respectively. CONCLUSIONS: Our findings suggest, at peri-MAC concentrations, these general anesthetics do not preferentially depress lumbar dorsal horn neurons with ascending projections compared to those with no identifiable ascending projections.

Original languageEnglish (US)
Pages (from-to)985-990
Number of pages6
JournalAnesthesia and Analgesia
Volume106
Issue number3
DOIs
StatePublished - Mar 2008

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Posterior Horn Cells
General Anesthetics
Isoflurane
Propofol
Halothane
Hot Temperature
Neurons
Anesthetics
Anesthesia
Laminectomy
Interneurons
Spinal Cord
Electrodes
Depression
Injections

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

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Immobilizing doses of halothane, isoflurane or propofol, do not preferentially depress noxious heat-evoked responses of rat lumbar dorsal horn neurons with ascending projections. / Barter, Linda S; Mark, Laurie O.; Jinks, Steven L.; Carstens, Earl; Antognini, Joseph F.

In: Anesthesia and Analgesia, Vol. 106, No. 3, 03.2008, p. 985-990.

Research output: Contribution to journalArticle

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abstract = "BACKGROUND: The spinal cord is an important site where volatile anesthetics decrease sensation and produce immobility. Beyond this knowledge, our understanding of a site of anesthetic action is limited. Previous evidence suggests that dorsal horn neurons with ascending projections may be more susceptible to depression by general anesthetics than local spinal interneurons. In this study we evaluated the effects of volatile and injectable general anesthetics on lumbar dorsal horn neurons with and without ascending projections. METHODS: Thirty-seven adult male rats underwent laminectomies at C1, for placement of a stimulating electrode, and T13/L1, for extracellular recording from the spinal cord dorsal horn. Neuronal responses to heat were evaluated under two doses of halothane, isoflurane, or propofol anesthesia. RESULTS: Under both halothane and isoflurane anesthesia, increasing the dose from 0.8 to 1.2 minimum alveolar concentration (MAC) had no significant effect on heat-evoked responses in neurons that had ascending projections identified via antidromic stimulation (AD) or those without ascending projections (nAD). Heat responses in AD neurons 1 min after IV administration of 3 and 5 mg/kg of propofol were reduced to 60{\%} ± 18{\%} (mean ± se) and 39{\%} ± 14{\%} of control respectively. Similarly, in nAD neurons responses were reduced to 56{\%} ± 14{\%} and 50{\%} ± 10{\%} of control by 3 and 5 mg/kg propofol respectively. CONCLUSIONS: Our findings suggest, at peri-MAC concentrations, these general anesthetics do not preferentially depress lumbar dorsal horn neurons with ascending projections compared to those with no identifiable ascending projections.",
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