乙酰胆碱、蛙皮素和P物质对人食管下括约肌张力调节的细胞内信号转导机制

The study on the intracellular signal transduction pathways in contraction of the human lower esophageal sphincter induced by acetylcholine, bombesin and substance P

目的观察蛋白激酶C（PKC）和钙调蛋白信号转导通路在乙酰胆碱、蛙皮素和P物质对人食管下括约肌钩状纤维和套索纤维张力调节中的作用。方法应用PKC信号通路特异性阻断剂H7和钙调蛋白信号通路特异性阻断剂CGS9343B，以食管和胃底环形肌作对照，测定抑制套索纤维和钩状纤维肌细胞收缩的情况。结果乙酰胆碱与蛙皮素和P物质引起的收缩，应用H7（5±1）％、（5±2）％、（6±2）％和无钙培养（4±1）％、（6±1）％、（3±1）％的方法，可以有效阻断钩状纤维的收缩（22±1）％、（23±1）％、（24±1）％；以CGS9343B（3±1）％、（4±2）％、（6±1）％和4mmol/L锶离子处理（5±2）％、（3±1）％、（6±2）％可以有效阻断套索纤维（23±2）％、（24±2）％、（26±1）％的收缩。结论人食管下括约肌的套索纤维细胞依赖钙调蛋白信号通路和内源性钙离子释放产生最大收缩效应。钩状纤维细胞依赖PKC信号通路和外源性钙离子流入产生最大收缩效应。

Objective To investigate the roles of two distinct intracellular signal transduction pathways：Protein Kinase C （PKC）-dependent and calmodulin-dependent, in the contractile mechanism of the clasp and sling fibers, the two parts of human lower esophageal sphincter, in comparison with circular muscle from gastric fundus and esophagus. Meanwhile the roles of extracellular and intracellular Ca2 ＋ in this process were studied. Methods （ 1 ） Cells from the clasp fiber, the sling fiber, the circular muscles of the esophagus and the gastric fundus were contracted by exposure to aeetylcholine, bombesin and substance P. （2） When Protein Kinase C （PKC）-dependent pathway inhibitors H7, calmodulin-dependent pathway inhibitor CGS9343 B, Ca2＋ -free medium or substitution of 4 mmol/L Sr2 ＋ for Ca2 ＋ were used, the cells were incubated in appropriate solution for 5 min before addition of agonists. The length of each cell was measured by video-based motion edge-detection system. Results Maximal contraction of the cells of the clasp fibers was blocked by H7 （ 5 ±1 ） %, （ 5 ±2 ） %, （6 ± 2 ） % and by incubation in Ca2＋ -free medium （4 ± 1 ） %, （6 ± 1 ） %, （3 ± 1 ） % ,but not by the CGS9343B and 4mmol/L Sr2~. By contrast, Maximal contraction of the cells from sling fibers was blocked only by CGS9343B （ 3± 1 ） %, （4 ± 2） %, （6 ± 1 ） % and 4 mmol/L Sr2＋ （5 ± 2） %, （3 ±1 ） %, （6 ±2） %. Conclusion Contraction of the sling fibers and the circular muscle of the gastric fundus depends on release of intracellular calcium and activation of a calmodulin-dependent pathway. While contraction of the clasp fibers and the circular muscle of the esophagus depends on influx of extracellular calcium and activation of a PKC-dependent signal transduction pathway.