Background/Aims: In addition to its cardiotonic effect, levosimendan has been thought to have multiple cardiovascular benefits, including anti-inflammatory and anti-apoptotic. Phosphatase and tensin homolog deleted on chromosome ten (PTEN) has been revealed to be up-regulated in circumstances of coronary microembolization (CME), and the PTEN signaling pathway mediates myocardial apoptosis in swine after CME. However, whether this functional protein could be modified by pretreatment of

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... an in models of CME has not been disclosed yet. Methods: Swine CME was induced by intra-coronary injection of inertia plastic microspheres (diameter 42μm) into left anterior descending coronary, with or without pretreatment of levosimendan or PTEN siRNA. Echocardiologic measurements, Terminal-deoxynucleotidyl Transferase Mediated Nick End Labeling (TUNEL) staining and western blotting were applied to assess their functional, morphological and molecular effects in CME. Results: PTEN mRNA and protein were aberrantly up-regulated in cardiomyocytes following CME. Furthermore, down-regulation of PTEN in vivo via siRNA was associated with an improved cardiac function, attenuated myocardial apoptosis, and concomitantly inhibited expressions of key proapoptotic proteins such as caspase-3. Interestingly, levosimendan could markedly attenuate PTEN expression and inhibit myocardial apoptosis, therefore partially reverse cardiac dysfunction. Conclusion: Modulation of PTEN was probably as a potential mechanism involved in the beneficial effects of pretreatment of levosimendan to cardiac function and apoptosis in animal models of CME.