Isoflurane postconditioning prevents opening of the mitochondrial permeability transition pore through inhibition of glycogen synthase kinase 3beta.
BACKGROUND
Postischemic administration of volatile anesthetics activates reperfusion injury salvage kinases and decreases myocardial damage. However, the mechanisms underlying anesthetic postconditioning are unclear.


METHODS
Isolated perfused rat hearts were exposed to 40 min of ischemia followed by 1 h of reperfusion. Anesthetic postconditioning was induced by 15 min of 2.1 vol% isoflurane (1.5 minimum alveolar concentration) administered at the onset of reperfusion. In some experiments, atractyloside (10 microm), a mitochondrial permeability transition pore (mPTP) opener, and LY294002 (15 microm), a phosphatidylinositol 3-kinase inhibitor, were coadministered with isoflurane. Western blot analysis was used to determine phosphorylation of protein kinase B/Akt and its downstream target glycogen synthase kinase 3beta after 15 min of reperfusion. Myocardial tissue content of nicotinamide adenine dinucleotide served as a marker for mPTP opening. Accumulation of MitoTracker Red 580 (Molecular Probes, Invitrogen, Basel, Switzerland) was used to visualize mitochondrial function.


RESULTS
Anesthetic postconditioning significantly improved functional recovery and decreased infarct size (36 +/- 1% in unprotected hearts vs. 3 +/- 2% in anesthetic postconditioning; P < 0.05). Isoflurane-mediated protection was abolished by atractyloside and LY294002. LY294002 inhibited isoflurane-induced phosphorylation of protein kinase B/Akt and glycogen synthase kinase 3beta and opened mPTP as determined by nicotinamide adenine dinucleotide measurements. Atractyloside, a direct opener of the mPTP, did not inhibit phosphorylation of protein kinase B/Akt and glycogen synthase kinase 3beta by isoflurane but reversed isoflurane-mediated cytoprotection. Microscopy showed accumulation of the mitochondrial tracker in isoflurane-protected functional mitochondria but no staining in mitochondria of unprotected hearts.


CONCLUSIONS
Anesthetic postconditioning by isoflurane effectively protects against reperfusion damage by preventing opening of the mPTP through inhibition of glycogen synthase kinase 3beta.
Feng
Jianhua
J
Institute of Anesthesiology, University Hospital Zurich, Zwitzerland.
Lucchinetti
Eliana
E
Ahuja
Preeti
P
Pasch
Thomas
T
Perriard
Jean-Claude
JC
Zaugg
Michael
M
D018685:Anesthetics, Inhalation / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D015153:Blotting, Western; D002867:Chromones / Q000494:pharmacology; D004396:Coloring Agents; D003213:Conditioning, Psychological / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors*; D000071679:Glycogen Synthase Kinase 3 beta; D006439:Hemodynamics / Q000187:drug effects; D066298:In Vitro Techniques; D007530:Isoflurane / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008297:Male; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D009203:Myocardial Infarction / Q000201:enzymology / Q000473:pathology / Q000517:prevention & control; D009206:Myocardium / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D009930:Organic Chemicals; D010539:Permeability / Q000187:drug effects; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects
D018685:Anesthetics, Inhalation; D002867:Chromones; D004396:Coloring Agents; D004791:Enzyme Inhibitors; D009025:Morpholines; D009930:Organic Chemicals; C107472:red dye CMXRos; D009243:NAD; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D007530:Isoflurane; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3