Inhibitory effect of gallic acid on voltage-gated Na+ channels in rat cardiomyocytes

Gallic acid (GA) has a protective effect on the cardiovascular system. To study its cardiac electrophysiological effects, voltage-gated Na⁺ channel currents (I_Na) were recorded in rat cardiomyocytes using whole-cell patch clamp techniques. Moreover, the effects of GA on aconitine-induced arrhythmias were assessed using electrocardiograms in vivo. We found that the current–voltage characteristic curve (I-V curve) of I_Na significantly shifted in the presence of 1, 3, and 10 μmol/L of GA. The peak sodium current density (I_Na-Peak) was reduced from −84.02 ± 5.68 pA/pF to −65.78 ± 3.96 pA/pF with 1 μmol/L, −54.45 ± 5.18 pA/pF with 3 μmol/L, and −44.20 ± 4.35 pA/pF with 10 μmol/L, respectively. GA shifted the steady-state activation curve of I_Na and recovery curve to the right and the steady-state inactivation curve to the left. The observed inhibitory effect was comparable to that of amiodarone. GA pre-treatment significantly prolonged the onset of fatal ventricular fibrillation. Our results indicated that GA inhibited I_Na in rat ventricular myocytes and aconitine-induced arrhythmias in vivo. These results suggest the potential of GA for development as a novel anti-arrhythmic therapeutic.