Lundman L, Juhn S K, Bagger-Sjöbäck D, Svanborg C
Department of Otorhinolaryngology, Karolinska Hospital, Karolinska Institute, Stockholm, Sweden.
Acta Otolaryngol. 1992;112(3):524-9. doi: 10.3109/00016489209137435.
Sensorineural hearing loss associated with otitis media may be due to passage of ototoxic substances such as bacterial toxins and antibiotics, from the middle ear into the inner ear. The round window membrane is the most likely route for such transport. The aim of this study was to analyze the extent of endotoxin passage through the normal round window membrane. The round window membranes of 19 chinchillas were exposed in vivo to Gelfoam soaked in purified Haemophilus influenzae type b endotoxin at a concentration of 45,000 endotoxin units per ml (EU/ml) during 3 to 24 h. Endotoxin levels in the perilymph were measured with Limulus Amaebocyte Lysate or Quantitative Chromogenic Limulus Amaebocyte Lysate. Endotoxin was detected in half of the inner ears at concentrations close to the detection limit (approximately 4 EU/ml). The results suggest that the normal round window membrane efficiently protects the inner ear against the passage of bacterial endotoxins from the middle ear cavity. It is unlikely that endotoxin at concentrations found in the middle ear secretion during otitis media can traverse the round window membrane in sufficient amount to cause inner ear deterioration.
与中耳炎相关的感音神经性听力损失可能是由于耳毒性物质（如细菌毒素和抗生素）从中耳进入内耳所致。圆窗膜是此类转运最可能的途径。本研究的目的是分析内毒素通过正常圆窗膜的程度。19只龙猫的圆窗膜在体内暴露于浸泡有纯化的b型流感嗜血杆菌内毒素的明胶海绵中，浓度为每毫升45,000内毒素单位（EU/ml），持续3至24小时。用鲎试剂或定量显色鲎试剂测定外淋巴中的内毒素水平。在一半的内耳中检测到内毒素，其浓度接近检测限（约4 EU/ml）。结果表明，正常的圆窗膜能有效保护内耳免受中耳腔内细菌内毒素的侵入。中耳炎期间中耳分泌物中发现的内毒素浓度不太可能以足够的量穿过圆窗膜而导致内耳恶化。
