Resveratrol protects rabbit ventricular myocytes against oxidative stress-induced arrhythmogenic activity and Ca2+ overload

Aim: To investigate whether resveratrol suppressed oxidative stress-induced arrhythmogenic activity and Ca2+ overload in ventricular myocytes and to explore the underlying mechanisms. Methods: Hydrogen peroxide (H2O2, 200 mu mol/L)) was used to induce oxidative stress in rabbit ventricular myocytes. Cell shortening and calcium transients were simultaneously recorded to detect arrhythmogenic activity and to measure intracellular Ca2+ ([Ca2+](i)). Ca2+/calmodulin-dependent protein kinases II (CaMKII) activity was measured using a CaMKII kit or Western blotting analysis. Voltage-activated Na+ and Ca2+ currents were examined using whole-cell recording in myocytes. Results: H2O2 markedly prolonged Ca2+ transient duration (CaTD), and induced early afterdepolarization (EAD)-like and delayed afterdepolarization (DAD)-like arrhythmogenic activity in myocytes paced at 0.16 Hz or 0.5 Hz. Application of resveratrol (30 or 50 mu mol/L) dose-dependently suppressed H2O2-induced EAD-like arrhythmogenic activity and attenuated CaTD prolongation. Co-treatment with resveratrol (50 mu mol/L) effectively prevented both EAD-like and DAD-like arrhythmogenic activity induced by H2O2. In addition, resveratrol markedly blunted H2O2-induced diastolic [Ca2+](i) accumulation and prevented the myocytes from developing hypercontracture. In whole-cell recording studies, H2O2 significantly enhanced the late Na+ current (I-Na,I-L) and L-type Ca2+ current (I-Ca,I-L) in myocytes, which were dramatically suppressed or prevented by resveratrol. Furthermore, H2O2-induced ROS production and CaMKII activation were significantly prevented by resveratrol. Conclusion: Resveratrol protects ventricular myocytes against oxidative stress-induced arrhythmogenic activity and Ca2+ overload through inhibition of I-Na,I-L/I-Ca,I-L, reduction of ROS generation, and prevention of CaMKII activation.