Molecular biological study of the endolymphatic sac

应用PCR和原位杂交技术检测了大鼠内淋巴囊（ES）上皮Na^+通道（ENaC）和激素受体（醛固酮、加压素和心钠素受体）的mRNA表达。逆转录大鼠ES RNA后，用特异于ENaC（-亚基）和醛固酮、血管加压素V1 a、V1 b、V2、ANP-A和ANP-B受体的引物对通过PCR扩增cDNA。PCR产物亚克隆后，测定核酸序列。用35 S标记的cRNA探针进行原位杂交，检测ENaC及其受体在ES中的表达，用PCR检测ENaC、醛固酮、血管加压素V1 a和ANP-A受体在ES中的表达，原位杂交结果显示醛固酮受体存在于ES中间部的上皮细胞中，而未显示加压素V1 a和ANP-A受体的存在。结果提示醛固酮参与了ES的Na^+转运。

The expression of mRNAs encoding epithelial Na^+ channel (ENaC) and hormone receptors (aldosterone, vasopressin and ANP receptors) in the endolymphatic sac (ES) of the rat was examined by PCR and in situ hybridization. After reverse-transcription of rat ES RNA,cDNA was amplified by PCR using pairs of primers specific to ENaC (-subunit) and aldosterone, vasopressin V1a, V1b, V2, ANP-A and ANP-B receptors. After subcloning of the PCR products, the nucleic acid sequences were determined. Next, the localization of expression of ENaC and those receptors in the ES was examined by in situ hybridization using 35S-labeled cRNA probes.Expressions of EnaC,aldosterone, vasopressin V1a and ANP-A receptors were detected in the ES by PCR.In situ hybridization revealed the presence of aldosterone receptor in epithelial cells of the intermediate portion of the ES,while it failed to show the presence of vasopressin V1a and ANP-A receptors. The results suggest the involvement of aldosterone in Na^+ transport of the ES.