Airway epithelical Cl channel regulation by iNOS gene

越来越多的证据表明，一氧化氮（NO）在气道中合成和释放，从而在各种气道功能中发挥作用。在本实验中，以确定是否上皮来源的NO参与调节Cl分泌，因此，水分泌到气道腔，我们研究了分离的人支气管上皮细胞在体外。用膜片钳技术研究了高钙溶液加缓激肽或NO供体S-硝基乙酰-N-青霉胺和硝普钠引起的Cl-选择性电流增加和通道开放概率增加。这种效果是伴随着相应的增加NO选择性电流，通过极谱法使用NO选择性电极，和诱导的存在下的组成型NO合酶（cNOS）样免疫反应。另一方面，E. coli、IL-1β、TNF-α或IFN-γ均增加Cl-电导和单个Cl-通道电流。这种效应同样伴随着培养基中NO浓度的增加，但是，基于Noclonal分析和免疫细胞化学，这些刺激上调了iNOS mRNA和iNOS蛋白的表达。这些作用被14元大环内酯类和糖皮质激素剂量依赖性地抑制。因此，大环内酯类和类固醇类药物可能是治疗气道高分泌的潜在药物。

There is increasing evidence that nitric oxide (NO) is synthesized and released in the airways, thereby playing a role in a variety of airway functions. In the present experiment, to determine whether epithelium-derived NO is involved in the regulation of Cl secretion and, hence, water secretion into the airway lumen, we studied isolated human bronchial epithelial cells in vitro. Patch clamp studies of isolated airway epithelium showed that intracellular adition of high calcium solution plus bradykinin, or the NO donors S-nitroacetyl-N-penicillamine and nitroprusside caused an increase in Cl-selective current and open probability of luminal Cl channel. This effect was accompanied by the corresponding increase in NO-selective electrical current, as measured by a polarography using an NO-selective electrode, and induction of the presence of constitutive NO synthase (cNOS)-like immunoreactivities. On the other hand, stimulation of the cells with endotoxin from E. coli, interleukin-1β, tumor necrosis factor-α, or interferon-γ each increased Cl conductance and single Cl channel current. This effect was likewise accompanied by the increase in NO concentration in the medium, but, based on Nothern analysis and immunocytochemistry, expressions of iNOS mRNA and iNOS protein were upregulated by these stimuli. Futhermore,these effects were dose-dependently inhibited by 14-membered macrolides and glucocorticosteroids. Therefore, macrolides and steroids may be therapeutic potential for the treatment of airway hypersecretion in the inflamed airways.