汞对大鼠三叉神经节电压依赖性钙通道电流及[Ca2+]i的影响

目的 观察Hg2+对大鼠三叉神经细胞膜电压依赖性钙通道电流(Ica)及胞内游离Ca,2+浓度的影响,探讨汞对三叉神经细胞毒性作用的机制.方法 全细胞膜片钳方法记录不同剂量的H2+作用下三叉神经细胞膜Ica的变化,并用激光共聚焦和Fluo-3/AM荧光探针标记技术,从单个细胞水平检测H2+寸胞内游离Ca2+浓度瞬间动态变化的影响.结果 0.01、0.10、1.00、10.00μmol/L H2+可使三叉神经细胞Ica电流幅值分别减少(1.80±0.32)%、(23.04±9.46)%、(58.20±7.90)%、(82.00±5.77)%,给Hg2+5min之内抑制作用即可达最大效应,洗脱未见明显电流恢复.0.01、0.10、1.00μmol/LH2+可使三叉神经细胞游离Ca2+浓度即时增加(2.500±83)%、(82.81±35.36)%、(222.70±62.48)%;预先用10 μmol/Lnifedipine处理细胞10 min,可在一定程度上减弱Hg2+的升钙作用,并延缓升钙的时间.结论 Hg2+对神经细胞膜Ica幅度的抑制作用与H2+抑制电压依赖性钙通道有关;H2+导致的神经细胞内游离Ca2+度升高与细胞内钙库释放有关.

Effect of Hg2+ on voltage-dependent calcium channels and intraceflular free calcium in trigeminal ganglion neurons of rats

Objective To investigate the effects of Hgv on voltage-dependent calcium channels and intracellular free calcium in trigeminal ganglion neurons of rats and explore the toxicity mechanism of Hg2+ on these neurons. Methods Whole cell patch-clamp technique was used to determine ICa of voltage-dependent calcium channels in trigeminal ganglion neurons of rats. Intracellular free calcium was measured to explore [Ca2+]i dynamic changes from a single cell level by laser scanning confocal microscopy and fluorescence probe techniques. Results 0.01,0.10,1.00 and 10.00 μmol/L Hg2+ could reduce voltage-dependent calcium channel currents ICa by(1.80±K).32)%, (23.04±9.46)%, (58.20±7.90)% and(82.00±5.77)%in trigeminal ganglion neurons. The inhibiting effects reached their maximum in 5 minutes and could not be reversed significantly during wash with Hg2+-free solution. Also, 0.01,0.10 and 1.00 μmol/L Hg2+ increased intracellular free calcium concentrations by (2.50±0.83)%, (82.81±35.36)% and (222.70±62.48)% in trigeminal ganglion neurons.Pre-administrated trigeminal ganglion neurons with nifedipine for 10 minutes could decrease the effects and delay the effecting time. Conclusion The inhibition of Hg2+ on the voltage-dependent calcium channel currents ICa depends on voltage-dependent calcium channels. And the increase of intraceilular free calcium concentration in trigeminal ganglion neurons induced by Hg2+ is related to the release of intracellular stored calcium. However, the relationship between them needs further investigation.