Anesthetic-induced preconditioning delays opening of mitochondrial permeability transition pore via protein Kinase C-epsilon-mediated pathway.
BACKGROUND
Cardioprotection by volatile anesthetic-induced preconditioning (APC) involves activation of protein kinase C (PKC). This study investigated the importance of APC-activated PKC in delaying mitochondrial permeability transition pore (mPTP) opening.


METHODS
Rat ventricular myocytes were exposed to isoflurane in the presence or absence of nonselective PKC inhibitor chelerythrine or isoform-specific inhibitors of PKC-delta (rottlerin) and PKC-epsilon (myristoylated PKC-epsilon V1-2 peptide), and the mPTP opening time was measured by using confocal microscopy. Ca-induced mPTP opening was measured in mitochondria isolated from rats exposed to isoflurane in the presence and absence of chelerythrine or in mitochondria directly treated with isoflurane after isolation. Translocation of PKC-epsilon was assessed in APC and control cardiomyocytes by Western blotting.


RESULTS
In cardiomyocytes, APC prolonged time necessary to induce mPTP opening (261 +/- 26 s APC vs. 216 +/- 27 s control; P < 0.05), and chelerythrine abolished this delay to 213 +/- 22 s. The effect of isoflurane was also abolished when PKC-epsilon inhibitor was applied (210 +/- 22 s) but not in the presence of PKC-delta inhibitor (269 +/- 31 s). Western blotting revealed translocation of PKC-epsilon toward mitochondria in APC cells. The Ca concentration required for mPTP opening was significantly higher in mitochondria from APC rats (45 +/- 8 microM x mg control vs. 64 +/- 8 microM x mg APC), and APC effect was reversed with chelerythrine. In contrast, isoflurane did not protect directly treated mitochondria.


CONCLUSIONS
APC induces delay of mPTP opening through PKC-epsilon mediated inhibition of mPTP opening, but not through PKC-delta. These results point to the connection between cytosolic and mitochondrial components of cardioprotection by isoflurane.
Pravdic
Danijel
D
Department of Anesthesiology, Medical College of Wisconsin, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. dpravdic@mcw.edu
Sedlic
Filip
F
Mio
Yasushi
Y
Vladic
Nikolina
N
Bienengraeber
Martin
M
Bosnjak
Zeljko J
ZJ
D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D015153:Blotting, Western; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D018613:Microscopy, Confocal; D008929:Mitochondria, Heart / Q000187:drug effects / Q000502:physiology*; D033681:Mitochondrial Membrane Transport Proteins / Q000187:drug effects*; D000083162:Mitochondrial Permeability Transition Pore; D032383:Myocytes, Cardiac / Q000187:drug effects; D010539:Permeability / Q000187:drug effects; D051745:Protein Kinase C-delta / Q000037:antagonists & inhibitors / Q000502:physiology; D051744:Protein Kinase C-epsilon / Q000037:antagonists & inhibitors / Q000502:physiology*; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
D000777:Anesthetics; D004791:Enzyme Inhibitors; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon