Effect of Sodium Metabisulfite on Potassium Currents in Rat Dorsal Root Ganglion Neurons

The effects of SO_ 2 derivative-SMB, a food preservative, on transient outward potassium currents (TOCs) and delayed rectifier potassium currents (I_ K) in rat DRG neurons were investigated using whole cell configuration of patch-clamp technique. The results showed that SMB increased the amplitudes of TOCs and I_ K in a concentration-and voltage-dependent manner. 10 μmol L -1 SMB did not affect the activation process of TOCs. Before and after application of 10 μmol L -1 SMB, the half-activation voltages of TOCs were (3.15±2.29) mV and (4.72±1.92) mV (N=8, P0.05), respectively, and their slope factors were not changed. But the inactivation curve of TOCs was shifted to positive potentials, the half-inactivation voltages of TOCs were (-53.6±0.45) mV and (-38.85±0.68) mV (N=8, P0.01), without changing the slope factors too. 10 μmol L -1 SMB affected the activation process of I_ K. The half-activation voltages of I_ K were (-11.98±3.50) mV and (-33.21±5.67) mV (N=8, P0.01), and their slope factors were not changed before and after application of 10 μmol L -1 SMB. The enhancement effects of SMB on TOCs and I_ K were mainly due to the shift of the steady-state activation curve of I_ K in the hyperpolarizing direction and the shift of steady-inactivation of TOCs to more positive potentials. It is suggested that SO_ 2 derivative-SMB cause the increase of extracellular K + and induce the disturbance of rat DRG neuronal functions. Fig 6, Ref 16