大鼠食管肌条对电刺激的反应及机制研究

The effects and mechanism of electrical stimulation on esophageal muscle in rat： an experimental study

目的探讨大鼠食管体部离体肌条收缩张力值与电刺激参数的相关关系，及其收缩机制。方法选取雄性健康WISTAR大鼠20只并取离体食管肌条，以刺激模式分别为电压（1.5、3.0、5.0、8.0 V），频率（5、10、20 Hz），脉宽25 ms，刺激时间为3 s的单相方波进行电刺激，观察分析电刺激参数与肌条张力的相关关系；选取雄性健康WISTAR大鼠50只，随机分为对照组、阿托品组、酚妥拉明组、NO合酶阻滞剂组（L-NNA）、河豚毒素组各10例，各组取离体食管肌条，首先给予能引起肌条有效收缩的电刺激（单相方波，5.0 V，20 Hz，脉宽25 ms）并记录肌条张力，然后各组分别给予阿托品、酚妥拉明、L-NNA、河豚毒素干预10 min后再次进行相同参数电刺激并记录肌条张力，与对照组比较，以明确神经递质是否能影响电刺激对食管肌条的作用。结果在频率20 Hz，脉宽25 ms的单相方波下，1.5 V组肌条张力收缩峰值为0 g。5.0 V组收缩峰值大于3.0 V组、小于8.0 V组，4组间及后3组任意两组间差异均有统计学意义（P〈0.05），电压与峰值之间呈显著正相关（R〉0.1，P〈0.05）。在电压5.0 V，脉宽25 ms的单相方波下，10 Hz组收缩峰值大于5 Hz组、小于20 Hz组，3组间及任意两组间差异均有统计学意义（P〈0.05），频率与峰值之间呈显著正相关（R〉0.1，P〈0.05）；阿托品组干预前后电刺激食管肌条收缩峰值有统计学差异（P〈0.05），酚妥拉明、L-NNA、河豚毒素处理组及对照组干预前后差异无统计学意义（P〉0.05）。结论电刺激大鼠食管离体肌条可引起有效收缩且在一定范围内收缩强度与电压、频率成正相关。电刺激收缩机制不依赖于胆碱能神经、肾上腺素能等神经的调节，不受神经递质的影响。

Objective To explore the correlation between smooth muscle contraction and stimulation parameters, and mechanism of electrical stimulation on the esophageal body muscle strips in normal rats. Methods A segment of lower part esophagus of 20 healthy male WISTAR rats was obtained. Single phase square wave（ width 25 ms）was used and the electrical stimulation lasted for 3 s with varied electrical parameter （ current ： 1.5 V, 3.0 V, 5.0 V, 8. 0 V ; frequency ： 5 Hz, 10 Hz, 20 Hz）. The correlation between tension and stimulation parameters was studied.Fifty healthy male rats were divided randomly into control group（ n = 10）, ATR group（ n = 10）, P HT group （n = 10）, L-NNA group （n = 10）, TTX group （n = 10）. Respective drugs were given 10 minutes before lower part of esophagus was stimulated with single phase square wave （ 5.0 V ; 20 Hz ; width 25 ms）, the tension was recorded and compared among groups. Results At frequency 20 Hz and width 25 ms, the peak value of contraction in 1.5 V group was 0 g. The peak value of contraction in 5.0 V group was more than 3.0 V group and less than 8.0 V group（P〈0. 05）. There was significant difference among the 4 groups and any 2 groups of the latter 3 groups. There was positive correlation between voltage and peak value（R〉0. 1 ,P〈0.05） .At current 5.0 V and width 25 ms ,the peak value of contraction in 10 Hz group was more than 5 Hz group and less than 20 Hz group （ P 〈 0.05 ）. There was significant difference among the 3 groups and any 2 groups.There was a positive correlation between the peak value of contraction and stimulation frequency（R〉0. 1, P〈0. 05）.The peak value of contraction was not different after intervention with phentolamine, L-NNA, TTX, while that of atropine group（P〈0. 05） was, compared with stimulation 10 min before（P〉0. 05）. Conclusion The electrical stimulation of esophageal muscle in normal rats could cause effective contraction immediately. The peak value of contraction is correlated positively with volgage and frequency of electrical stimulation. The effect of electrical stimulation on esophageal muscle is not influenced by nurontransmeters.