Aims: Catestatin (CST) limits myocardial ischaemia/reperfusion (I/R) injury with unknown mechanisms. Clearly phosphoinositide-3-kinase (PI3K), protein-kinase-C (PKC) isoforms, including intra-mitochondrial PKC, mitochondrial-KATP (mitoKATP) channels and subsequent reactive-oxygen-species (ROS)-signalling play important roles in postconditioning cardioprotection, preventing mitochondrial permeability transition pore (mPTP) opening. Therefore, we studied the role of these extra- and intra-mitochondrial factors in CST-induced protection. Methods and Results: Isolated rat hearts and H9c2 cells underwent I/R and oxidative stress, respectively. In isolated hearts CST (75nM, CST-Post) given in early-reperfusion significantly reduced infarct-size, limited post-ischaemic contracture, and improved recovery of developed left ventricular pressure. PI3K inhibitor, LY-294002 (LY), large spectrum PKC inhibitor, Chelerythrine (CHE), specific PKC inhibitor (εV1-2), mitoKATP channel blocker, 5-Hydroxydecanoate (5HD) or ROS scavenger, 2-mercaptopropionylglycine (MPG) abolished the infarct-sparing effect of CST. Notably the CST-induced contracture limitation was maintained during co-infusion of 5HD, MPG or εV1-2, but it was lost during co-infusion of LY or CHE. In H9c2 cells challenged with H2O2, mitochondrial-depolarization (an index of mPTP-opening studied with JC1-probe) was drastically limited by CST (75nM). Conclusions: Our results suggest that the protective signalling pathway activated by CST includes mitoKATP channels, ROS-signalling and prevention of mPTP opening, with a central role for upstream PI3K/Akt and PKCs. In fact, all inhibitors completely abolished CST-infarct-sparing effect. Since CST-anti-contracture effect cannot be explained by intra-mitochondrial mechanisms (PKC activation and mitoKATP channel opening) or ROS-signalling, it is proposed that these downstream signals are part of a reverberant loop which re-activates upstream PKCs, which therefore play a pivotal role in CST-induced protection.
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|Titolo:||Catestatin reduces myocardial ischaemia/reperfusion injury: involvement of PI3K/Akt, PKCs, mitochondrial K(ATP) channels and ROS signalling.|
|Data di pubblicazione:||2013|
|Appare nelle tipologie:||1.1 Articolo in rivista|