Lactate, not glucose, up-regulates mitochondrial oxygen consumption both in sham and lateral fluid percussed rat brains

Joseph E. Levasseur, Beat Alessandri, Michael Reinert, Tobias Clausen, Zhengwen Zhou, Nabil Altememi, Ross Bullock

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

OBJECTIVE: Failure of energy metabolism after traumatic brain injury may be a major factor limiting outcome. Although glucose is the primary metabolic substrate in the healthy brain, the well documented surge in tissue lactate after traumatic brain injury suggests that lactate may provide an energy need that cannot be met by glucose. We hypothesized, therefore, that administration of lactate or the combination of lactate and supraphysiological oxygen may improve mitochondrial oxidative respiration in the brain after rat fluid percussion injury. We measured oxygen consumption (VO2) to determine what effects glucose, lactate, oxygen, and the combination of lactate and oxygen have on mitochondrial respiration in both injured and uninjured rat brain tissue. METHODS: Anesthetized Sprague-Dawley rats were intubated and ventilated with either 0.21 or 1.0 fraction of inspired oxygen (FIO2). Brain tissue from acute sham animals was subjected in vitro to 1.1 mM, 12 mM and 100 mM concentrations of glucose and L-lactate. In another group, injury (fluid percussion injury of 2.5 ± 0.02 atmospheres) was induced over the left hemisphere. The VO2 of μg amounts of brain tissues were measured in a microrespirometry system (Cartesian diver). RESULTS: The VO2 was found to be independent of glucose concentrations, but dose-dependent for lactate. Moreover, the lactate dependent VO2s were all significantly higher than those generated by glucose. Injured rats on FIO2 0.21 had brain tissue VO2 rates that were significantly lower than those of shams or preinjury levels. In injured rats treated with FIO2 1.0, the reduction in VO2 levels was prevented. Injured rats that received an intravenous infusion of 100 mM lactate had VO2 rates that were significantly higher than those obtained with FIO2 1.0. Combined treatment further boosted the lactate generated VO2 rates by approximately 15%. CONCLUSION: Glucose sustains mitochondrial respiration at a low level "fixed" rate because, despite increasing its concentration nearly 100-fold, it cannot up-regulate VO2 after fluid percussion injury. Lactate produces a dose-dependent VO2 response, possibly enabling mitochondria to meet the increased energy needs of the injured brain.

Original languageEnglish
Pages (from-to)1122-1130
Number of pages9
JournalNeurosurgery
Volume59
Issue number5
DOIs
StatePublished - Nov 1 2006
Externally publishedYes

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Oxygen Consumption
Lactic Acid
Up-Regulation
Glucose
Brain
Percussion
Oxygen
Respiration
Wounds and Injuries
Atmosphere
Intravenous Infusions
Energy Metabolism
Sprague Dawley Rats
Mitochondria

Keywords

  • Brain injury
  • Glucose
  • Lactate
  • Oxygen
  • Oxygen consumption

ASJC Scopus subject areas

  • Clinical Neurology
  • Surgery

Cite this

Levasseur, J. E., Alessandri, B., Reinert, M., Clausen, T., Zhou, Z., Altememi, N., & Bullock, R. (2006). Lactate, not glucose, up-regulates mitochondrial oxygen consumption both in sham and lateral fluid percussed rat brains. Neurosurgery, 59(5), 1122-1130. https://doi.org/10.1227/01.NEU.0000245581.00908.AF

Lactate, not glucose, up-regulates mitochondrial oxygen consumption both in sham and lateral fluid percussed rat brains. / Levasseur, Joseph E.; Alessandri, Beat; Reinert, Michael; Clausen, Tobias; Zhou, Zhengwen; Altememi, Nabil; Bullock, Ross.

In: Neurosurgery, Vol. 59, No. 5, 01.11.2006, p. 1122-1130.

Research output: Contribution to journalArticle

Levasseur, JE, Alessandri, B, Reinert, M, Clausen, T, Zhou, Z, Altememi, N & Bullock, R 2006, 'Lactate, not glucose, up-regulates mitochondrial oxygen consumption both in sham and lateral fluid percussed rat brains', Neurosurgery, vol. 59, no. 5, pp. 1122-1130. https://doi.org/10.1227/01.NEU.0000245581.00908.AF
Levasseur, Joseph E. ; Alessandri, Beat ; Reinert, Michael ; Clausen, Tobias ; Zhou, Zhengwen ; Altememi, Nabil ; Bullock, Ross. / Lactate, not glucose, up-regulates mitochondrial oxygen consumption both in sham and lateral fluid percussed rat brains. In: Neurosurgery. 2006 ; Vol. 59, No. 5. pp. 1122-1130.
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AU - Zhou, Zhengwen

AU - Altememi, Nabil

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N2 - OBJECTIVE: Failure of energy metabolism after traumatic brain injury may be a major factor limiting outcome. Although glucose is the primary metabolic substrate in the healthy brain, the well documented surge in tissue lactate after traumatic brain injury suggests that lactate may provide an energy need that cannot be met by glucose. We hypothesized, therefore, that administration of lactate or the combination of lactate and supraphysiological oxygen may improve mitochondrial oxidative respiration in the brain after rat fluid percussion injury. We measured oxygen consumption (VO2) to determine what effects glucose, lactate, oxygen, and the combination of lactate and oxygen have on mitochondrial respiration in both injured and uninjured rat brain tissue. METHODS: Anesthetized Sprague-Dawley rats were intubated and ventilated with either 0.21 or 1.0 fraction of inspired oxygen (FIO2). Brain tissue from acute sham animals was subjected in vitro to 1.1 mM, 12 mM and 100 mM concentrations of glucose and L-lactate. In another group, injury (fluid percussion injury of 2.5 ± 0.02 atmospheres) was induced over the left hemisphere. The VO2 of μg amounts of brain tissues were measured in a microrespirometry system (Cartesian diver). RESULTS: The VO2 was found to be independent of glucose concentrations, but dose-dependent for lactate. Moreover, the lactate dependent VO2s were all significantly higher than those generated by glucose. Injured rats on FIO2 0.21 had brain tissue VO2 rates that were significantly lower than those of shams or preinjury levels. In injured rats treated with FIO2 1.0, the reduction in VO2 levels was prevented. Injured rats that received an intravenous infusion of 100 mM lactate had VO2 rates that were significantly higher than those obtained with FIO2 1.0. Combined treatment further boosted the lactate generated VO2 rates by approximately 15%. CONCLUSION: Glucose sustains mitochondrial respiration at a low level "fixed" rate because, despite increasing its concentration nearly 100-fold, it cannot up-regulate VO2 after fluid percussion injury. Lactate produces a dose-dependent VO2 response, possibly enabling mitochondria to meet the increased energy needs of the injured brain.

AB - OBJECTIVE: Failure of energy metabolism after traumatic brain injury may be a major factor limiting outcome. Although glucose is the primary metabolic substrate in the healthy brain, the well documented surge in tissue lactate after traumatic brain injury suggests that lactate may provide an energy need that cannot be met by glucose. We hypothesized, therefore, that administration of lactate or the combination of lactate and supraphysiological oxygen may improve mitochondrial oxidative respiration in the brain after rat fluid percussion injury. We measured oxygen consumption (VO2) to determine what effects glucose, lactate, oxygen, and the combination of lactate and oxygen have on mitochondrial respiration in both injured and uninjured rat brain tissue. METHODS: Anesthetized Sprague-Dawley rats were intubated and ventilated with either 0.21 or 1.0 fraction of inspired oxygen (FIO2). Brain tissue from acute sham animals was subjected in vitro to 1.1 mM, 12 mM and 100 mM concentrations of glucose and L-lactate. In another group, injury (fluid percussion injury of 2.5 ± 0.02 atmospheres) was induced over the left hemisphere. The VO2 of μg amounts of brain tissues were measured in a microrespirometry system (Cartesian diver). RESULTS: The VO2 was found to be independent of glucose concentrations, but dose-dependent for lactate. Moreover, the lactate dependent VO2s were all significantly higher than those generated by glucose. Injured rats on FIO2 0.21 had brain tissue VO2 rates that were significantly lower than those of shams or preinjury levels. In injured rats treated with FIO2 1.0, the reduction in VO2 levels was prevented. Injured rats that received an intravenous infusion of 100 mM lactate had VO2 rates that were significantly higher than those obtained with FIO2 1.0. Combined treatment further boosted the lactate generated VO2 rates by approximately 15%. CONCLUSION: Glucose sustains mitochondrial respiration at a low level "fixed" rate because, despite increasing its concentration nearly 100-fold, it cannot up-regulate VO2 after fluid percussion injury. Lactate produces a dose-dependent VO2 response, possibly enabling mitochondria to meet the increased energy needs of the injured brain.

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