Kaempferol protects cardiomyocytes against anoxiaireoxygenation injury via mitochondrial pathway mediated by SIRT1

Mitochondria mediated apoptosis is a critical mechanism of anoxia/ reoxygenation (A/R) induced injury in cardiomyocytes. Kaemplerol (Kae) is a natural polyphenol and a type of flavonoid, which has been demonstrated to protect myocardium against ischemia/reperfusion (I/R) injury. However, the mechanism is still not fully elucidated. We hypothesize that Kae may improve the mitochondrial function during I/R injury via a potential signal pathway. In this study, an in vitro I/R model was replicated On neonatal rat primary cardiomyocytes by A/R treatment. Cell viability was monitored by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sullophenyl)-2 H-tetrazolium (MTS) assay. The levels of intracellular reactive oxygen species, mitochondrial membrane potential (Delta psi m) and apoptosis were determined by flow cylometry. Protein expression was detected by Western Blotting. mPTP opening and the activity of caspase-3 were measured by colorimetric method. The results showed that Kae effectively enhanced the cell viability and decreased the I/R release in cardiomyocyles subjected to A/R injury. Kae reduced the AIR-induced reactive oxygen species generation, the loss of Awn, and the release of cytochrome c from mitochondria into cytosol. Kae inhibited the A/R-stimulated mPTP opening and activation of caspase-3, and ultimate decrease in cardiomyocytes apoptosis. Furthermore, we found Kae upregulated Human Silent Information Regulator Type 1 (SIRT1) expression, indicating SIRT1 signal pathway likely involved the cardioprotection of Kae. Sirtinol, a SIRT1 inhibitor, abolished the protective effect of Kae in cardiomyocytes subjected to AIR. Additionally, Kae significantly increased the expression of Bcl-2. Thus, we firstly demonstrate that Kae protects cardiomyocytes against AIR injury through mitochondrial pathway mediated by SIRT1. (C) 2015 Published by Elsevier B.V.