焦亚硫酸钠对大鼠背根节神经元钠电流的影响

Effects of Sodium Metabisulfite on Sodium Currents in Rat Dorsal Root Ganglion Neurons

应用全细胞膜片钳技术,研究了食品添加剂——焦亚硫酸钠(sodium metabisulfite,SMB)对大鼠背根节神经元河豚毒素敏感型(tetrodotoxin-sensitive,TTX-S)钠电流和河豚毒素不敏感型(tetrodotoxin-resistant,TTX-R)钠电流的影响。结果表明,SMB可增大TTX-S钠电流和TTX-R钠电流,且具剂量依赖性和电压依赖性。10μmol/L的SMB不影响TTX-S钠电流的激活过程,但却非常显著地影响其失活过程。TTX-S钠电流的半数激活电压在给药前后分别为(-28.06±1.30)mV和(-29.92±1.42)mV(n=8,P>0.05),斜率因子不改变;其半数失活电压在给药前后分别为(-71.33±0.87)mV和(-57.88±0.98)mV(n=8,P<0.01),斜率因子不改变。5μmol/L的SMB显著影响TTX-R钠电流的激活过程和失活过程,给药前后,TTX-R钠电流的半数激活电压分别为(-10.44±0.62)mV和(-16.62±0.82)mV(n=8,P<0.01),半数失活电压分别为(-33.39±0.38)mV和(-40.94±0.60)mV(n=8,P<0.01),均不改变其斜率因子。说明SMB显著增大TTX-S和TTX-R钠电流,使TTX-R钠电流的激活过程提前,抑制TTX-S和TTX-R钠电流的失活过程,从而导致神经细胞的兴奋性增加。这也意味着,二氧化硫及其衍生物亚硫酸氢盐对背根节神经元钠通道具有生理调节作用和病理生理学影响。

Effects of sodium metabisulfite（SMB）,a food preservative,on tetrodotoxin-sensitive（TTX-S） and tetrodotoxin-resistant（TTX-R） sodium channels in cultured post-natal dorsal root ganglion（DRG） neurons were studied using the whole cell configuration of patch-clamp technique.The results showed SMB increased the sodium currents of TTX-S and TTX-R in a concentration-and voltage-dependent manner.10 μmol/L SMB did not affect the activation process of TTX-S,the half-activation voltages of TTX-S were（-28.06 ± 1.30） and（-29.92 ± 1.42） mV（n = 8,P〉0.05） before and after application of 10 μmol/L SMB,respectively,and their slope factors were not changed.But the inactivation curve of TTX-S was shifted to positive potentials,the half-inactivation voltages of TTX-S were（-71.33 ± 0.87） and（-57.88 ± 0.98） mV（n = 8,P〈0.01） before and after application of SMB（10 μmol/L）,respectively,without changing the slope factors.5 μmol/L SMB affected the activation and inactivation process of TTX-R.Before and after application of 5 μmol/L SMB,the half-activation voltages of TTX-R were（-10.44 ± 0.62） and（-16.62 ± 0.82） mV（n = 8,P〈0.01）,respectively,the half-inactivation voltages of TTX-R were（-33.39 ± 0.38） and（-40.94 ± 0.60） mV（n = 8,P〈0.01）,respectively,and their slope factors were not changed.These results lead the conclusions： SMB significantly increased the sodium currents of TTX-S and TTX-R in rat DRG neurons.SMB shifted the steady-state activation curve of TTX-R to more negative potentials and inhibited their inactivation process of TTX-S and TTX-R,and excitability of the neurons was increased by SMB.It implies that there are physiological modulation and pathophysiologic effects of sulfur dioxide and its derivative bisulfite on rat dorsal root ganglion neurons.