Epigallocatechin-3-Gallate Protects Na+ Channels in Rat Ventricular Myocytes Against Sulfite

Sulfite (bisulfite/sulfite) can affect voltage-gated sodium (Na+) channels (VGSC) in a concentration-dependent manner in isolated rat ventricular myocytes. In this study, the effect of epigallocatechin-3-gallate (EGCG) on VGSC in isolated ventricular myocytes was studied. Ventricular myocytes were exposed to 10 mu M bisulfite/sulfite for 10 min, and EGCG was then administered in different concentrations (10, 30, 50 mu g ml(-1)). Decreased activity of superoxide dismutase, catalase (CAT) and glutathione peroxidase (GPx) was observed after bisulfite/sulfite exposure, with significant increase in Na+ currents (I (Na)) and alterations in half-activation voltage and half-inactivation voltage. Intracellular reactive oxygen species (ROS) such as hydrogen peroxide (H2O2), hydroxyl (OH center dot), and superoxide anion (O (2) (center dot-) ) were increased. After EGCG treatment, activity of the aforementioned enzymes increased while the ROS level decreased. The effects progressed with increasing amounts of EGCG, up to a level similar to blank control at the dose of 50 mu g ml(-1) EGCG, EGCG also reduced the I (Na) and reversed the alterations in half-activation voltage and half-inactivation voltage. In conclusion, EGCG could protect Na+ channels in rat ventricular myocytes against the oxidative damage induced by sulfite as a scavenger of the ROS.