Table 1.
Screen of flavonoids on mEAG1 channel gating
| Compound | Applied concentration | ΔV1/2 | P-value | EC50 | Deactivation time constant | P-value | EC50 | n |
| mV | µM | ms | µM | |||||
| Acacetin | 50 µM | 0.4 ± 2.0 | 1 | 5.97 ± 1.50 | 0.73 | 7 | ||
| Apigenin | 10 µM | −5.3 ± 1.9 | 0.63 | 5.35 ± 0.85 | 0.66 | 4 | ||
| Catechin | 50 µM | 1.6 ± 1.9 | 0.81 | 4.58 ± 0.45 | 0.87 | 5 | ||
| Fisetin | 10 µM | −9.6 ± 1.9 | 0.03a | 3.5 ± 0.4 | 6.49 ± 0.96 | 0.04a | 6.6 ± 3.7 | 8 |
| Galangin | 10 µM | −3.3 ± 1.9 | 0.53 | 5.50 ± 0.49 | 0.21 | 5 | ||
| Kaempferol | 10 µM | −10.8 ± 0.02 | 0.02a | 9.67 ± 0.79 | 0.01a | 7 | ||
| Luteolin | 10 µM | −11.0 ± 2.5 | 0.05a | 4.7 ± 2.4 | 7.63 ± 2.44 | 0.22 | 8.7 ± 0.8 | 5 |
| Myricetin | 10 µM | −8.0 ± 5.7 | 0.60 | 5.85 ± 1.65 | 0.28 | 4 | ||
| Narnegin | 50 µM | −5.0 ± 1.9 | 0.65 | 5.38 ± 0.59 | 0.23 | 5 | ||
| Quercetin | 10 µM | −10.1 ± 3.5 | 0.05a | 2.4 ± 1.0 | 8.80 ± 1.25 | 0.01a | 6.6 ± 3.8 | 7 |
| Estradiol | 50 µM | 0.1 ± 1.0 | 0.99 | 6.73 ± 1.99 | 0.87 | 4 | ||
| cAMP | 10 mM | 0.3 ± 0.8 | 0.91 | 4.56 ± 0.32 | 0.82 | 5 | ||
| cGMP | 10 mM | −0.7 ± 1.0 | 0.93 | 4.00 ± 0.40 | 0.60 | 5 |
The responses of mEAG1 channel gating to screened flavonoids are shown. The screened compounds were applied to patches recorded in the inside-out configuration of the patch-clamp technique. Each compound was applied to at least four patches expressing mEAG1 channels, and data shown are mean ± SEM. To screen for changes in the steady-state properties, we quantified the flavonoid-induced shifts in the V1/2 of the conductance–voltage relation. P-values report the significance and were obtained from two-tailed t tests comparing the V1/2 in the presence and absence of the applied compound. The average rate of deactivation in the absence of flavonoids (not included in the table) was 4.1 ± 0.2 ms (n = 30). P-values represent significance of two-tailed t tests used to compare the rate of deactivation in the presence and absence of flavonoids. Concentration–response experiments were performed for three of the potentiating flavonoids: fisetin, luteolin, and quercetin. Hill equations were used to quantify the half-maximal concentrations for both the shift in the V1/2 of the conductance relationship and for the rate of channel deactivation. n reports the number of observations made for each flavonoid on the shifts of the V1/2 of the conductance–voltage relation and the slowing of deactivation.
Significant differences (P < 0.05).