title: Involvement of Cyclophilin D and Calcium in Isoflurane-induced Preconditioning.
abstract: BACKGROUND
  The mitochondrial permeability transition pore (PTP) has been established as an important mediator of ischemia-reperfusion-induced cell death. The matrix protein cyclophilin D (CypD) is the best known regulator of PTP opening. Therefore, the authors hypothesized that isoflurane, by inhibiting the respiratory chain complex I, another regulator of PTP, might reinforce the myocardial protection afforded by CypD inhibition.
  
  
  METHODS
  Adult mouse or isolated cardiomyocytes from wild-type or CypD knockout (CypD-KO) mice were subjected to ischemia or hypoxia followed by reperfusion or reoxygenation. Infarct size was assessed in vivo. Mitochondrial membrane potential and PTP opening were assessed using tetramethylrhodamine methyl ester perchlorate and calcein-cobalt fluorescence, respectively. Fluo-4 AM and rhod-2 AM staining allowed the measurement, by confocal microscopy, of Ca transient and Ca transfer from sarcoplasmic reticulum (SR) to mitochondria after caffeine stimulation.
  
  
  RESULTS
  Both inhibition of CypD and isoflurane significantly reduced infarct size (-50 and -37%, respectively) and delayed PTP opening (+63% each). Their combination had no additive effect (n = 6/group). CypD-KO mice displayed endogenous protection against ischemia-reperfusion. Isoflurane depolarized the mitochondrial membrane (-28%, n = 5), decreased oxidative phosphorylation (-59%, n = 5), and blunted the caffeine-induced Ca transfer from SR to mitochondria (-22%, n = 7) in the cardiomyocytes of wild-type mice. Importantly, this transfer was spontaneously decreased in the cardiomyocytes of CypD-KO mice (-25%, n = 4 to 5).
  
  
  CONCLUSIONS
  The results suggest that the partial inhibitory effect of isoflurane on respiratory complex I is insufficient to afford a synergy to CypD-induced protection. Isoflurane attenuates the Ca transfer from SR to mitochondria, which is also the prominent role of CypD, and finally prevents PTP opening.
authors.affiliation: From INSERM UMR-1060, CarMeN Laboratory, Université Lyon-1, Faculté de Médecine Rockefeller, Lyon, France (G.T., P.C., M.A., E.C.-L., R.H., B.P., Y.T., A.G., M.O.); Service d'Anesthésie Réanimation, Hôpital Louis Pradel, Hospices Civils de Lyon, Lyon, France (P.C.); INSERM UMR-1046, Université Montpellier 1, Université Montpellier 2, Centre Hospitalier Universitaire de Montpellier, Montpellier, France (J.F., A.L.); and Service d'Explorations Fonctionnelles Cardiovasculaires and CIC de Lyon, Hôpital Louis Pradel, Hospices Civils de Lyon, Lyon, France (M.O.).
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Teixeira
authors.forename: Pascal
authors.initials: P
authors.lastname: Chiari
authors.forename: Jeremy
authors.initials: J
authors.lastname: Fauconnier
authors.forename: Maryline
authors.initials: M
authors.lastname: Abrial
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Couture-Lepetit
authors.forename: Rania
authors.initials: R
authors.lastname: Harisseh
authors.forename: Bruno
authors.initials: B
authors.lastname: Pillot
authors.forename: Alain
authors.initials: A
authors.lastname: Lacampagne
authors.forename: Yves
authors.initials: Y
authors.lastname: Tourneur
authors.forename: Abdallah
authors.initials: A
authors.lastname: Gharib
authors.forename: Michel
authors.initials: M
authors.lastname: Ovize
mesh_terms: D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000081406:Peptidyl-Prolyl Isomerase F; D021983:Cyclophilins / Q000378:metabolism*; D042967:Electron Transport Complex I / Q000378:metabolism; D019157:Ischemic Preconditioning, Myocardial; D007530:Isoflurane / Q000008:administration & dosage*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000503:physiopathology*
chemical_list: D018685:Anesthetics, Inhalation; D000081406:Peptidyl-Prolyl Isomerase F; C000631446:PPIF protein, mouse; D007530:Isoflurane; D021983:Cyclophilins; D042967:Electron Transport Complex I; D002118:Calcium