Myricetin inhibits Kv 1 . 5 channels in HEK 293 cells

Myricetin (Myr) is a f lavonoid that exerts anti-arrhythmic effects. However, its potential effects on ion channels have remained elusive. The aim of the present study was to investigate the effects of Myr on Kv1.5 channels in HEK293 cells. The current of Kv1.5 channels (Ikur) in HEK293 cells was recorded using the whole-cell patch-clamp technique and the expression of the Kv1.5 protein was measured using western blot analysis 24 h after treatment with Myr. The results showed that 5 μM Myr significantly reduced Ikur from 215.04±40.59 to 77.72±17.94 pA/pF (P<0.05; n=5). Myr increased the current suppression from 0 to 0.31±0.12 and 0.55±0.11 over 5 or 20 min, respectively. In addition, Ikur decreased from 376.23±1.30 to 270.19±4.28 pA/pF when the frequency was increased from 0.5 to 4 Hz in HEK293 cells treated with 10 μM Myr for 5 min. Furthermore, Myr reduced hKv1.5 protein expression in a dose-dependent manner. These results demonstrated that Myr inhibited Ikur and the expression of hKv1.5 in HEK293 cells in a dose-, timeand frequency-dependent manner. These observations partly explained the mechanisms by which Myr exerts anti-arrhythmic effect.