title: In Vitro Induction of Endothelial Apoptosis of the Post-Hypoxic Blood-Brain Barrier by Isoflurane but Not by Sevoflurane and Midazolam.
abstract: BACKGROUND
  The effects of anesthetics on the injured brain continue to be the subject of controversial discussion. Since isoflurane has recently been shown to induce apoptosis of cerebral endothelial cells, this study compared different anesthetic compounds regarding their potential to induce cerebro-vascular apoptosis.
  
  
  METHODS
  The in vitro model of the blood-brain barrier used in this study consisted of astrocyte-conditioned human umbilical vein endothelial cells (AC-HUVEC) has been used. After 24 h of deep hypoxia and reoxygenation or control treatment, AC-HUVEC were exposed to 0, 0.5, 1.0, or 2.0 times the minimum alveolar concentration of isoflurane or sevoflurane, or 0, 75, 150, or 300 nM of midazolam for 2 h. After 24 h, AC-HUVEC were harvested, and the degree of apoptosis was assessed by means of Western blots for the Bax and Bcl-2 ratio and, for controls and the highest concentration groups, terminal deoxynucleotidyl-mediated dUTP-biotin nick end labeling (TUNEL).
  
  
  RESULTS
  Without hypoxic pretreatment, 2.0 MAC of isoflurane slightly increased TUNEL intensity compared to control and sevoflurane, but without any significant changes in the Bax and Bcl-2 ratio. After hypoxic pretreatment, exposure to isoflurane led to a multifold increase in the Bax and Bcl-2 ratio in a dose dependent manner, which was also significantly higher than the ratio observed in the 2 MAC sevoflurane group. TUNEL intensity in the post-hypoxic 2 MAC isoflurane group was increased by a factor of 11 vs. control and by 40 vs. sevoflurane. Sevoflurane and midazolam did not significantly alter these markers of apoptosis, when compared to the control group.
  
  
  CONCLUSIONS
  Isoflurane administered after hypoxia elevates markers of apoptosis in endothelial cells transdifferentiated to the cerebro-vascular endothelium. Endothelial apoptosis may be a previously underestimated mechanism of anesthetic neurotoxicity. Administration of high concentrations of isoflurane in experimental settings may have negative effects on the blood-brain barrier.
authors.affiliation: Department of Anesthesiology, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Dittmar
authors.affiliation: Department of Anesthesiology, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Petermichl
authors.affiliation: Department of Anesthesiology, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Regina
authors.initials: R
authors.lastname: Lindner
authors.affiliation: Department of Anesthesiology, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Sinner
authors.affiliation: Department of Anesthesiology, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Bernhard M
authors.initials: BM
authors.lastname: Graf
authors.affiliation: Department of Neurology, Bezirksklinikum Regensburg, University of Regensburg, Regensburg, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Schlachetzki
authors.affiliation: Department of Anesthesiology, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Gruber
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001812:Blood-Brain Barrier / Q000378:metabolism; D015687:Cell Hypoxia; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D007530:Isoflurane / Q000494:pharmacology*; D008738:Methyl Ethers / Q000494:pharmacology*; D008874:Midazolam / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D000077149:Sevoflurane; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D008738:Methyl Ethers; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D000077149:Sevoflurane; D007530:Isoflurane; D008874:Midazolam