大鼠急性有机磷杀虫剂及其混剂中毒的单肌纤维肌电图研究

Stimulation single fiber electromyography in rats with myasthenia induced by organophosphorus insecticides and their mixtures poisoning

目的 探讨应用电刺激单肌纤维肌电图 (SSFEMG)在不同刺激频率 (5、10、2 0Hz)时检测神经 -肌接头传导功能作为有机磷农药及其混剂中毒引起肌无力效应指标的意义。方法 利用SSFEMG技术观察有机磷类 (乐果、辛硫磷 )、氨基甲酸酯类 (灭多威 )农药及其混剂 (辛硫磷 +灭多威、乐果 +灭多威 )对大鼠神经 -肌接头传导功能的影响 ,并在染毒前和染毒后 1h测定大鼠全血胆碱酯酶 (ChE)活力。结果 各染毒组大鼠肌无力发生的情况为 :乐果 5 / 9,辛硫磷 5 / 10 ,灭多威 0 / 9,辛硫磷+灭多威 8/ 8,乐果 +灭多威 5 / 5 ;肌无力大鼠单肌纤维动作电位平均连续差 (MCD)明显高于对照组 ,辛硫磷和乐果组中的肌无力大鼠MCD明显高于同组肌力正常者 ,差异均有显著性 (P <0 .0 5 )。刺激频率为 10Hz和 2 0Hz的SSFEMG检测结果与大鼠肌无力症状一致性均较好 ;肌无力的出现与ChE的抑制程度不完全一致。结论 有机磷所致肌无力与神经 -肌接头传导功能异常关系密切 ,刺激频率为 10Hz和 2 0Hz的SSFEMG可用作有机磷农药所致肌无力的一个效应指标。

Objective To study the neuromuscular function and its relation with the occurrence of myasthenia in rats poisoned by dimethoate(D),phoxim(P),methomyl(M),M+D and M+P respectively. Methods The stimulation single fiber electromyography(SSFEMG) at different stimulus frequencies(5,10 and 20 Hz) was used.The whole blood cholinesterase(ChE) activity was measured 1 h before and after poisoning. Results (1)Myasthenia occurred in 5 out of 9,5 out of 10,5 out of 5,and 8 out of 8 rats poisoned by D,P,M+D,and M+P,respectively.(2)The average mean consecutive differences(MCD) at 5,10,and 20 Hz in myasthenic rats were significantly higher than those of poisoned rats without myasthenia and the control ones.(3)SSFEMG changes at 5,10 and 20 Hz were significantly consistent with the clinical manifestation of myasthenia,especially at 10 Hz and 20 Hz.(4)ChE activity was significantly lower in rats with P or D poisoning while ChE inhibition was of no difference in rats with M,M+D,and M+P poisoning.In the D poisoning and P poisoning groups,there was no significant difference in ChE inhibition between the rats with and without myasthenia. Conclusion Muscle weakness was associated with neuromuscular transmission dysfunction,but not well correlated with ChE inhibition.The SSFEMG with stimulus frequency at 10 Hz or 20 Hz could be used to detect the neuromuscular dysfunction during myasthenia induced by organophosphate insecticides and their mixtures poisoning.