(−)‐Epigalocathine‐3‐gallate attenuates oxidative stress by modulation of redox signaling in H9c2 cultured rat cardiac myoblasts

Abstract

This study intended to explore the potential mechanism for the cardio-protection of (−)-epigalocathine-3-gallate (EGCg) on oxidative stress exerted by H2O2 or ischemia/reperfusion (IR) injury in H9c2 cultured rat cardiac myoblasts. H9c2 is a myogenic cell line from embryonic rat heart ventricle. When oxidative stress was induced in H9c2 cells by 0.4 or 1 mM H2O2, pretreatment with EGCg from 10 to 25 μM effectively recovered cell viability. Similarly, 5, or 10, or 15 μM EGCg supplementations significantly increased viability of cardiac cells with IR-simulated stress. The cardio-protection of EGCg involved in oxidation stress appears to act by reducing reactive oxygen species (ROS) and intracellular Ca2+. Measurements of dichlorofluorescein diacetate fluorescence for ROS generation showed that adding 5–50 μM EGCg to H2O2-treated H9c2 cells reduced their ROS generation back to the control levels. Intracellular Ca2+ measurements by fura-2 also indicated that 20 μM EGCg effectively reduced cytosolic Ca2+ overload in H2O2-disturbed H9c2 cells. This result is consistent with our recent findings in the rat model of IR that pretreatment with green tea extract protects cardiomyocytes from IR injury by preventing cytosolic Ca2+ overload and ROS generation (Liou et al., Pflügers Archiv-EJP, 2010). In addition, EGCg exerted the opposing effect of H2O2-induced oxidative stress in cultured H9c2 cells by modulation of β-catenin signaling and Cx43 phosphorylation/dephosphorylation. Taken together, this study suggested that EGCg might regulate β-catenin and Cx43 signaling and benefit cardio-protection via redox signaling in H9c2 cardiac cells. Grant: NSC-98-2320-B-005-001-MY2.