Vitamins C and E Modulate Neuronal Potassium Currents

We investigated the effects of vitamins C and E on the delayed-rectifier potassium current (IK_DR), which is important in repolarizing the membrane potential, and on the transient A-type potassium current (IK_A), which regulates neuronal firing frequency. The whole-cell patch-clamp technique was used to measure the currents from cultured Drosophila neurons derived from embryonic neuroblasts. The membrane potential was stepped to different voltages between −40 and +60 mV from a holding potential of −80 mV. IK_DR and IK_A measured in the vitamin C-containing solution (IK_DR 305 ± 16 pA, IK_A 11 ± 2 pA) were smaller than those measured in the control solution (488 ± 21 pA, IK_A 28 ± 3 pA). By contrast, IK_DR and IK_A measured in the vitamin E-containing solution (IK_DR 561 ± 21 pA, IK_A 31 ± 3 pA) were greater than those measured in the control solution (422 ± 15 pA, 17 ± 2 pA). These results indicate that vitamins C and E can modulate potassium current amplitudes and possibly lead to altered neuronal excitability.