Anesthetic-induced Preconditioning Delays Opening of Mitochondrial Permeability Transition Pore via Protein Kinase C-ϵ–mediated Pathway

Department of Anesthesiology, Medical College of Wisconsin, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
Anesthesiology (Impact Factor: 5.88). 07/2009; 111(2):267-74. DOI: 10.1097/ALN.0b013e3181a91957
Source: PubMed


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.
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.
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.
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.

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    • "In an in vivo rat model, Ludwig et al. (2004b) suggested that APC is mediated by opening of mK ATP channels and the subsequent generation of transient ROS, which activates protein kinases. In another study, Pravdic et al. (2009) inferred that APC is mediated by a PKC-δ-induced delay of mPTP opening. Lastly, another study showed that APC protected the mouse heart against reperfusion injury by preventing mPTP opening in an eNOS dependent manner, with NO • acting as both the trigger and the mediator of cardioprotection (Ge et al., 2010). "
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    • "An impressive body of evidence considers the activation of PKC (mainly its ε-isoform) as a major signaling component of anesthetic-induced preconditioning [34]. A previous study has shown that a specific inhibition of PKCε abolishes the protective effects that are induced by preconditioning stimuli [35]. "
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    • "Opening of MPTP is related to mitochondrial damage, and further triggers apoptotic pathways. In this study, we directly observed the inhibitory role of isoflurane pretreatment in H/R-induced opening of MPTP by the confocal imaging, supporting previous research results [20]. Because the mitochondria are major sites of ROS generation, we further observed that H/R-induced excess ROS production was prevented in the presence of isoflurane, supporting a link of excess ROS formation as an upstream signal to MPTP opening. "
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