Hara Shuya, Hazama Akihiro, Miyake Masao, Kojima Takashi, Sasaki Yasumasa, Shimazaki Jun, Dogru Murat, Tsubota Kazuo
Social Insurance Chukyo Hospital, Department of Ophthalmology, Nagoya, Japan.
Mol Vis. 2010 Nov 4;16:2279-85.
To investigate the presence of epithelial sodium channels (ENaC) in rabbit and human conjunctival epithelium and to test the effects of topical amiloride, a potassium-sparing diuretic that blocks the ENaC, on tear quantity in rabbits.
Both healthy normal human and rabbit conjunctival tissues underwent immunohistochemistry staining for ENaC-α and γ subunits as well as for reverse transcription-polymerase chain reaction (RT-PCR) for detection of ENaC-α and ENaC-γ subunit mRNA expression. Rabbits were instilled topical amiloride eye drops and tear function tests were performed before and after instillations.
Immunohistochemical staining for ENaC-α subunit in all rabbit eyes showed positive staining in apical and basal conjunctival epithelial cells. Human conjunctival epithelia revealed positive staining with ENaC-α antibody especially in the apical and basal layers. Immunohistochemistry staining with ENaC- γ antibody also revealed positive staining of the conjunctival epithelial cells especially in the basal layers. The ENaC-α mRNA was detected in samples from healthy white rabbit conjunctival epithelia, and ENaC-α and ENaC- γ mRNAs were detected in samples from healthy human conjunctival epithelia. The mean tear quantity showed a significant increase at 15 and 30 min compared to the pre-instillation value in eyes assigned to amiloride eye drops. The mean tear quantity at 15 and 30 min was significantly higher in the amiloride group compared to the control eyes.
Topical amiloride application appears to increase the quantity of preocular tears owing to inhibition of conjunctival epithelial sodium channels.
研究兔和人结膜上皮中上皮钠通道（ENaC）的存在情况，并测试局部应用氨氯吡咪（一种阻断ENaC的保钾利尿剂）对兔泪液量的影响。
对健康正常人及兔的结膜组织进行ENaC-α和γ亚基的免疫组织化学染色，以及逆转录-聚合酶链反应（RT-PCR）以检测ENaC-α和ENaC-γ亚基mRNA的表达。给兔局部滴注氨氯吡咪眼药水，并在滴注前后进行泪液功能测试。
所有兔眼ENaC-α亚基的免疫组织化学染色显示，结膜上皮细胞的顶端和基底细胞呈阳性染色。人结膜上皮用ENaC-α抗体染色也呈阳性，特别是在顶端和基底细胞层。用ENaC-γ抗体进行免疫组织化学染色也显示结膜上皮细胞呈阳性，特别是在基底细胞层。在健康白兔结膜上皮样本中检测到ENaC-α mRNA，在健康人结膜上皮样本中检测到ENaC-α和ENaC-γ mRNA。与滴注前相比，滴注氨氯吡咪眼药水的兔眼在15分钟和30分钟时平均泪液量显著增加。氨氯吡咪组在15分钟和30分钟时的平均泪液量显著高于对照眼。
局部应用氨氯吡咪似乎可通过抑制结膜上皮钠通道增加眼前泪液量。
