title: Inhibition of mitochondrial permeability transition enhances isoflurane-induced cardioprotection during early reperfusion: the role of mitochondrial KATP channels.
abstract: Inhibition of the mitochondrial permeability transition pore (mPTP) mediates the protective effects of brief, repetitive ischemic episodes during early reperfusion after prolonged coronary artery occlusion. Brief exposure to isoflurane immediately before and during early reperfusion also produces cardioprotection, but whether mPTP is involved in this beneficial effect is unknown. We tested the hypothesis that mPTP mediates isoflurane-induced postconditioning and also examined the role of mitochondrial KATP (mKATP) channels in this process. Rabbits (n = 102) subjected to a 30-min coronary occlusion followed by 3 h reperfusion received 0.9% saline (control), isoflurane (0.5 or 1.0 MAC) administered for 3 min before and 2 min after reperfusion, or the mPTP inhibitor cyclosporin A (CsA, 5 or 10 mg/kg) in the presence or absence of the mPTP opener atractyloside (5 mg/kg) or the selective mK(ATP) channel antagonist 5-hydroxydecanoate (5-HD; 10 mg/kg). Other rabbits received 0.5 MAC isoflurane plus 5 mg/kg CsA in the presence and absence of atractyloside or 5-HD. Isoflurane (1.0 but not 0.5 MAC) and CsA (10 but not 5 mg/kg) reduced (P < 0.05) infarct size (21% +/- 4%, 44% +/- 6%, 24% +/- 3%, and 43% +/- 6%, respectively, mean +/- sd of left ventricular area at risk; triphenyltetrazolium staining) as compared with control (42% +/- 7%). Isoflurane (0.5 MAC) plus CsA (5 mg/kg) was also protective (27% +/- 4%). Neither atractyloside nor 5-HD alone affected infarct size, but these drugs abolished protection by 1.0 MAC isoflurane, 10 mg/kg CsA, and 0.5 MAC isoflurane plus 5 mg/kg CsA. The results indicate that mPTP inhibition enhances, whereas opening abolishes, isoflurane-induced postconditioning. This isoflurane-induced inhibition of mitochondrial permeability transition is dependent on activation of mitochondrial KATP channels in vivo.
authors.affiliation: Departments of Anesthesiology, Pharmacology and Toxicology, and Medicine (Division of Cardiovascular Diseases), the Medical College of Wisconsin and the Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, and the Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin.
authors.forename: John G
authors.initials: JG
authors.lastname: Krolikowski
authors.forename: Martin
authors.initials: M
authors.lastname: Bienengraeber
authors.forename: Dorothee
authors.initials: D
authors.lastname: Weihrauch
authors.forename: David C
authors.initials: DC
authors.lastname: Warltier
authors.forename: Judy R
authors.initials: JR
authors.lastname: Kersten
authors.forename: Paul S
authors.initials: PS
authors.lastname: Pagel
mesh_terms: D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D007473:Ion Channels / Q000187:drug effects* / Q000502:physiology; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D009203:Myocardial Infarction / Q000517:prevention & control; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D015221:Potassium Channels / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D011817:Rabbits
chemical_list: D018685:Anesthetics, Inhalation; D007473:Ion Channels; D007530:Isoflurane; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D019869:Phosphatidylinositol 3-Kinases; D015221:Potassium Channels; D019253:Proto-Oncogene Proteins c-bcl-2; C117780:mitochondrial K(ATP) channel