膈神经电刺激对机械通气大鼠膈肌神经肌肉接头的影响

Effects of mechanical ventilation on diaphragmatic neuromuscular junction in rats

目的 研究机械通气以及机械通气联合膈神经电刺激对大鼠膈肌神经肌肉接头形态学的影响。方法 实验分组:对照组(CON组,n=6)、机械通气18 h组(MV组,n=6)、机械通气18 h联合假电刺激组(S-MS组,n=6)、机械通气18 h联合电刺激组(MS组,n=6)。通过生物信号采集系统检测膈肌收缩力,拟合刺激频率-收缩曲线,计算膈肌疲劳指数。通过HE染色观察膈肌标本肌纤维横截面积(cross-section area, CSA);通过膈肌整体免疫组织化学染色(IHC)联合激光共聚焦技术,观察神经肌肉接头(neuromuscular junction, NMJ)终板膜面积。结果 与CON组相比,MV组、S-MS组离体膈肌收缩力下降;与CON组(0.686 8±0.049 42)相比,MV组(0.360 3±0.066 89)、S-MS组(0.367 9±0.034 94)离体膈肌抗疲劳性下降,MS组(0.536 2±0.054 38)相对降低程度更低;与CON组[674.3(523.9,863.6)]相比,MV组[374.5(293.3,522.7)]、S-MS组[392.8(309.5,542.6)]膈肌CSA减少,MS组[592.7(425.1,820.0)]相对降低程度更低;与CON组[393.7(293.5,471.3)]相比,MV组[289.7(227.0,354.2)]、S-MS组[243.1(190.8,331.7)]膈肌终板膜面积减少,MS组[331.0(262.8,413.7)]相对降低程度更低。结论 机械通气导致大鼠膈肌功能障碍,且膈肌NMJ终板膜面积下降。通过10 min/h的双侧膈神经电刺激可改善机械通气引起的膈肌功能障碍和膈肌NMJ终板膜面积改变。

Objective To explore the effects of mechanical ventilation and mechanical ventilation com⁃bined with phrenic nerve electrical stimulation on the morphology of the phrenic nerve-diaphragm neuromuscular junction in rats.Methods The rats were divided into a control group(CON group,n=6);an 18-hour mechanical ventilation group(MV group,n=6);an 18-hour ventilation combined with sham electrical stimulation group(S-MS group,n=6);and an 18-hour ventilation combined with electrical stimulation group(MS group,n=6),in which the diaphragm contraction force was detected through the biological signal acquisition system,the stimula⁃tion frequency-contraction curve was fitted,and the muscle fatigue index was calculated.The muscle fiber cross-sectional area(CSA)of the diaphragm specimen was observed through HE staining;the endplate membrane area of the neuromuscular junction(NMJ)was observed through immunohistochemistry(IHC)staining of the diaphragm combined with laser confocal technology.Results As compared with the CON group,the contractility of isolated diaphragm muscles in the MV group and S-MS group decreased;the fatigue resistance of isolated diaphragm,as compared with the CON group(0.6868±0.04942),decreased in the MV group(0.3603±0.06689)and the S-MS group(0.3679±0.03494),with a greater decline in the MS group(0.5362±0.05438);as compared with the CON group[674.3(523.9,863.6)],diaphragm CSA was reduced in the MV group[374.5(293.3,522.7)]and S-MS group[392.8(309.5,542.6)],with a relatively lower reduction in the MS group[592.7(425.1,820.0)];as compared with the CON group[393.7(293.5,471.3)],the diaphragm endplate membrane area decreased in the MV group[289.7(227.0,354.2)]and S-MS group[243.1(190.8,331.7)],with a lower degree of reduction in the MS group[331.0(262.8,413.7).Conclusions Mechanical ventilation causes diaphragm dysfunction in rats and decreases the endplate membrane area of the diaphragm NMJ.Bilateral phrenic nerve electrical stimulation for 10 min/h can improve diaphragm dysfunction and changes in the endplate membrane area of the diaphragm NMJ caused by mechanical ventilation.