Hotta S, Takahashi M, Itoh T, Yamamura K
Department of Hygiene, Asahikawa Medical College, Hokkaido, Japan.
Acta Otolaryngol. 1998 Jun;118(3):362-8. doi: 10.1080/00016489850183449.
The inner ear distortion induced by gentamicin (GM), a type of aminoglycoside antibiotic, was examined in guinea-pigs. Previous studies which investigated the function of the eighth cranial nerve and organ of Corti using cochlear microphonics (CM) and compound action potential (CAP) reported ototoxicity following experimental exposure to GM. In this report, the effects of GM on the cochlea and the eighth cranial nerve were investigated systematically by measuring CM, CAP, summating potentials induced by 90 dB (SPL) tone burst, endocochlear potential (EP) and K+ ion concentration of the endolymph. Guinea-pigs were treated with a daily intramuscular injection of GM (60 mg in 1.5 cc) at a dose of 60 mg/kg during different treatment periods. The maximum output voltage of AP was decreased by injection of GM (60 mg/kg x 24). A decrease in the CM maximum output voltage and the elevation of CM pseudothreshold were typically seen after GM injection at a test frequency of 8 kHz and a decrease in CAP was also observed. Changes in EP during 3 min anoxia were observed, in particular a decrease in the absolute value of the negative potential. The endolymph K+ ion concentration remained unchanged. These findings indicate that the diffusion potentials decreased at the same time as reduction of maximum output voltage in CM induced by GM injection.
研究了豚鼠内耳由庆大霉素（GM，一种氨基糖苷类抗生素）引起的畸变。先前利用耳蜗微音器电位（CM）和复合动作电位（CAP）研究第八颅神经和柯蒂氏器功能的研究报告称，实验性暴露于庆大霉素后会出现耳毒性。在本报告中，通过测量CM、CAP、90分贝（声压级）短纯音诱发的总和电位、内淋巴电位（EP）以及内淋巴中的钾离子浓度，系统地研究了庆大霉素对耳蜗和第八颅神经的影响。在不同治疗期间，对豚鼠每日进行一次肌肉注射庆大霉素（60毫克溶于1.5毫升），剂量为60毫克/千克。注射庆大霉素（60毫克/千克×24次）后，动作电位的最大输出电压降低。在测试频率为8千赫时，注射庆大霉素后，通常会出现CM最大输出电压降低和CM伪阈值升高的情况，同时也观察到CAP降低。观察到3分钟缺氧期间EP的变化，特别是负电位绝对值的降低。内淋巴钾离子浓度保持不变。这些发现表明，由注射庆大霉素引起的CM最大输出电压降低的同时，扩散电位也降低。
