Schousboe L P, Ovesen T, Ledet T
Department of Otorhinolaryngology, Aarhus University Hospital, Denmark.
Int J Pediatr Otorhinolaryngol. 1997 Sep 18;41(3):279-90. doi: 10.1016/s0165-5876(97)00085-2.
The oxygen partial pressure of middle ear gas increases more than 3-fold upon insertion of ventilation tubes, while the carbon dioxide partial pressure decreases. Whereas the middle ear gas is normally equilibrated to venous gases and has an oxygen partial pressure of 43 mmHg, 138 mmHg is measured in ventilated ears. The present study was undertaken to compare the effects of these oxygen tensions on in vitro growth and glycoprotein secretion of rabbit middle ear epithelium and for comparison auditory meatal epithelium. Cultures were incubated in atmospheres of 7, 21 or 75% O2 in 5% CO2 and the remnant N2. The cell layer protein mass, [3H]thymidine-incorporation, DNA content and [3H]glucosamine-incorporation was measured in identical subcultures every third day during a 15-day period. In middle ear epithelium the DNA content, DNA synthesis and cell layer protein mass were significantly higher at 7% oxygen compared to 21% and 75%. In conclusion hyperoxia leads to decreased growth of middle ear epithelium in vitro. If applicable to in vivo conditions, this might contribute to the mechanism of action of ventilation tubes. Moreover the proliferation rate of auditory meatal epithelium exceeds that of middle ear epithelium both at 7 and 21% oxygen, an interesting point with regards to cholesteatoma pathogenesis.
插入通气管后，中耳气体的氧分压增加超过3倍，而二氧化碳分压降低。中耳气体通常与静脉气体平衡，氧分压为43 mmHg，而在通气的耳朵中测得的氧分压为138 mmHg。本研究旨在比较这些氧张力对兔中耳上皮细胞体外生长和糖蛋白分泌的影响，并与外耳道上皮进行比较。将培养物置于含5%二氧化碳和剩余氮气、氧气浓度分别为7%、21%或75%的环境中孵育。在15天的时间里，每隔三天对相同的传代培养物测量细胞层蛋白质质量、[3H]胸腺嘧啶核苷掺入量、DNA含量和[3H]葡糖胺掺入量。在中耳上皮中，与21%和75%的氧浓度相比，7%氧浓度下的DNA含量、DNA合成和细胞层蛋白质质量显著更高。总之，高氧导致中耳上皮细胞在体外生长减少。如果适用于体内情况，这可能有助于解释通气管的作用机制。此外，在7%和21%的氧浓度下，外耳道上皮的增殖率均超过中耳上皮，这在胆脂瘤发病机制方面是一个有趣的点。
