兔食管下括约肌与体部形态及毛酰胆碱对其功能影响的比较

A comparative study of acetylcholine on the function and morphology of lower esophageal sphincter and esophageal body in rabbits

目的:比较兔食管下括约肌(lower esophageal sphincter, LES)与食管体部形态变化,探讨食管体部平滑肌和LES细胞收缩功能及对乙酰胆碱的反应. 方法:利用光镜、透射电镜下观察LES与食管体部形态;测定LES与食管体部压力;使用激光共聚焦测定食管体部平滑肌和LES细胞内钙离子浓度,以及对乙酰胆碱(ACh)作用的反应. 结果:兔食管LES平滑肌细胞周围肌浆网及肌丝明显增加.LES平均压力为1.4±0.1 kPa;食管体部平均压力为. 0.6±0.1 kPa(P<0.01).兔食管LES平滑肌[Ca2+]i平均为156.1±4.8 nmol/L;兔食管体部平滑肌细胞[Ca2+]i平均为122.6±4.3 nmol/L(P<0.05).加入ACh后再次测定[Ca2+]i,LES平滑肌[Ca2+]i,平均为241.3±5.7 nmol/L与加入ACh前有显著差异(P<0.01);加入ACh后食管体部平滑肌[Ca2+]i平均为131.6±3.2 nmol/L,与加入ACh 前无显著差异(P>0.05). 结论:正常食管LES与体部平滑肌可能具有不同的生理学基础及收缩机制,食管体部对Ach诱导产生的收缩需要有细胞外钙的支持,而Ach对LES的收缩作用是通过细胞内钙离子的释放而产生的.

AIM: To compare the morphology of lower esophageal sphincter (LES) and esophageal body, and to explore the response of contraction of the smooth muscle of LES to acetylcholine (ACh). METHODS: The morphology of LES and esophageal body was examined under light microscope and electron microscope. The pressures of LES and the esophageal body were measured. The concentration of Ca2+ was determined with laser scanning confocal microscopy before and after ACh was administrated. RESULTS: The sarcoplasmic reticulum and myofilament were significantly increased in smooth muscle cells of LES. The pressures were 1.4++++++++++0.1 kPa and 0.6++++++++++0.1 kPa for LES and esophageal body, respectively, and there was significant difference between them (P <0.01). The mean concentrations of Ca2+ were 156.1+++++++++++++4.8 and 122.6+++++++++++4.3 nmol/L (P<0.05) in LES and esophageal body respectively before the application of ACh, and they became 241.3+++++++++5.7 nmol/L and 131.6±32nmol/L after ACh was applied.The changed concentration of Ca2+ in LES was significantly higher (P <0.01). CONCLUSION: Esophageal body and LES utilize Ca2+ from different sources to contract in response to Ach. In esophageal body, Ach-induced contraction requires influx of extracellular Ca2+, while in LES it might utilize intracel-lularly released Ca2+.