Simvastatin Attenuates Oxidant-Induced Mitochondrial Dysfunction in Cardiac Myocytes

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Abstract
3-Hydroxy-3-methylglutaryl–coenzyme A (HMG-CoA) reductase inhibitors (statins) can exert beneficial effects independently of serum cholesterol reduction by increasing the bioavailability of nitric oxide. However, it is unclear whether statins can exert such effects directly on cardiac myocytes and whether mitochondria are potential targets. Neonatal rat cardiac myocytes were cultured and subjected to oxidant stress (1 hour of 100 μmol/L H 2 O 2 ). Mitochondrial membrane potential, a key determinant of cardiomyocyte viability, was assessed by flow cytometric analysis of tetramethylrhodamine ethyl ester (TMRE)–loaded cells. Hydrogen peroxide significantly reduced mitochondrial membrane potential. Incubation of the cardiac myocytes in simvastatin (≥1 μmol/L) 1 hour before peroxide exposure significantly attenuated the loss of TMRE fluorescence. This effect was inhibited by the nitric oxide synthase inhibitor N G -nitro- l -arginine methyl ester (L-NAME) or the ATP-sensitive mitochondrial potassium channel (mitoK ATP ) blocker 5-hydroxydecanoate. Simvastatin attenuates mitochondrial membrane depolarization after exposure to oxidant stress. These findings provide primary evidence that myocytes can act as triggers and effectors in the cardioprotective cascade of simvastatin therapy. These results bear implications of statin therapy as a potential clinical application of pharmacological preconditioning.