Tan C T, Escoubet B, Van den Abbeele T, Friedlander G, Tran Ba Huy P, Herman P
Laboratoire d'Otologie Expérimentale, Faculté Lariboisière-St-Louis, Université Paris VII, France.
Acta Otolaryngol. 1997 Mar;117(2):284-8. doi: 10.3109/00016489709117788.
The efficacy of steroid therapy for the treatment of otitis media in children remains controversial, and a putative modulation of the middle ear epithelial function has to be demonstrated. Using the MESV cell line, short-circuit current (ISC) technique was used to evaluate changes in ion transport induced by glucocorticoids. Dexamethasone (DXM) produced a dose- and time-dependent increase in ISC in MESV cells. This effect was inhibited by specific glucocorticoid antagonist (RU-38486) and was related to a sodium transport, since the DXM-induced increase in ISC could be prevented or abolished i) by apical addition of the specific Na+ channel inhibitor benzamil; or ii) by substitution of sodium with N-Methyl-glucamine in the incubation medium. RNase protection assay revealed that DXM increased the expression of the alpha subunit sodium channel mRNA, which changes paralleled the modulation of ion transport. These data demonstrate that steroids up-regulate the trans-epithelial sodium transport in the middle ear epithelium. As far as these experimental data can be extrapolated to the in vivo situation, a component of the beneficial effect of steroid therapy for the treatment of otitis media may result from a corticosteroid-induced improvement in fluid clearance from the middle ear.
类固醇疗法治疗儿童中耳炎的疗效仍存在争议，中耳上皮功能的假定调节作用有待证实。利用MESV细胞系，采用短路电流（ISC）技术评估糖皮质激素诱导的离子转运变化。地塞米松（DXM）使MESV细胞的ISC呈剂量和时间依赖性增加。该效应被特异性糖皮质激素拮抗剂（RU - 38486）抑制，且与钠转运有关，因为DXM诱导的ISC增加可通过以下方式预防或消除：i）在顶端添加特异性Na +通道抑制剂苄amil；或ii）在孵育培养基中用N -甲基葡糖胺替代钠。核糖核酸酶保护试验显示，DXM增加了α亚基钠通道mRNA的表达，这种变化与离子转运的调节平行。这些数据表明，类固醇上调中耳上皮的跨上皮钠转运。就这些实验数据可外推至体内情况而言，类固醇疗法治疗中耳炎的有益作用部分可能源于皮质类固醇诱导的中耳液体清除改善。
