内皮素受体在人食管下括约肌上的分布及其作用

Distribution and role of endothelin receptors in human lower esophageal sphincter

目的通过检测各内皮素受体(ETR)亚型在人食管下括约肌(LES)上,特别是套索纤维和钩状纤维上的分布规律,探讨内皮素对LES收缩和舒张功能的作用。方法在罹患食管中上段癌患者的术后标本上,取LES的套索纤维和钩状纤维,并分别以食管下段和胃底部的环形肌肉作为对照。采用蛋白印迹法(Western Blot)、RT-PCR和半定量PCR(semi-qPCR)分析ETR在人LES上的分布规律。结果 ETR的A亚型(ETA)和B亚型(ETB)被确认都存在于LES上。ETR两个受体亚型的蛋白质和mRNA表达水平比较,差异均有统计学意义(F=533.841,P<0.01;F=72.291,P<0.01)。ETA显著高于ETB表达量(约为5∶1),差异有统计学意义;而同一受体亚型在钩状纤维(C)、套索纤维(S)、食管下端环形肌(E)、胃底环形肌(G)4个位点上的表达量比较差异无统计学意义(F=0.398,P=0.5329)。结论 ET受体,特别是ETA受体亚型在人LES的舒张、收缩功能调节中发挥着重要作用,是食管运动障碍性疾病治疗的靶向受体。

Objective Todetect thedistributionof endothelin receptors（ETR） in thehuman lower esophageal sphincter （LES）, especially on the clasp and sling smooth muscle fibers of the LES, and investigate the effects of endothelins on the contraction and diastole of LES. Methods The sling and clasp tissues from LES were obtained from esophageal carcinoma patients, and the circular muscle tissues from the esophagus and gastric fundus were served as controls. Western Blot, RT-PCR and semi-qPCR were employed to determine the distribution of ETR in human LES. Results Endothelin receptor type A （ETA） and endothelin receptor type B （ETB） were found in human LES. There were significantdifferences in the expression of protein and mRNA between two isoforms of ETR （F=533. 841, P 〈 0. 01 ; F=72.291, P 〈0.01）. The expression level of ETA was significantly higher than that of ETB （about 5：1）. For distribution of each isoform, inhere was no significant difference in the expression level among four sites of clasp fibers （C）, sling fibers（S）, lower esophageal sphincter （E） and gastric fundus circular muscle（G） （F= 0.398, P= 0. 5329）. Conclusions ETRs contribute to the adjustment of contraction and diastole of human LES, especially the ETA. ETRs are the potent therapeutic targets for esophageal mobility diseases.