噪声对豚鼠耳蜗外淋巴液中氨基酸浓度的影响

目的:观察噪声暴露于对耳蜗外淋巴液中氨基酸浓度的影响.方法:安静组和噪声组豚鼠分别暴露于安静环境(40 dB SPL)和白噪声(115 dB SPL) 2 h,抽取两组动物耳蜗外淋巴液,高效液相色谱(HPLC)荧光分光检测分析氨基酸浓度.结果:安静组动物耳蜗外淋巴液中含有14种氨基酸,与正常哺乳动物脑脊液氨基酸组成和含量十分接近.耳蜗外淋巴液中谷氨酸含量安静组为(6.6±0.2) μmol/L,而噪声组为(10.3±1.1) μmol/L, 后者比前者高55％,P<0.01.结论:噪声暴露可使耳蜗外淋巴中谷氨酸浓度明显提高, 推测这种提高可能和噪声导致毛细胞过度释放谷氨酸和谷氨酸转运体不能正常运转有关.

Effect of noise on concentration of amino acid in perilymph of guinea pig cochlea

Objective: To observe the effect of noise on the concentration of amino acids in perilymph of the cochlea. Methods: Guinea pigs were either exposed to white noise at 115 dB SPL for 2 h or maintained in silence (40 dB SPL). Perilymph was collected from the cochlea of the both groups. Free amino acids were determined by high-performance liquid chromatography with fluorescence detection. Results: Fourteen kinds of amino acids were detected in the perilymph of the cochlea from the silence group animals. The composition and concentration of these amino acids were similar to those in the guinea pig's cerebrospinal fluid. The concentration of glutamic acid in the cochlea of the noise group was significantly higher than that of the silence group (P<0.01). The average concentration of glutamic acid in the silence group was (6.6±0.2) μmol/L while in the noise group, it was (10.3±1.1) μmol/L. The latter was 55% higher than the former. Conclusion: The glutamic acid in the perilymph of the cochlea can be significantly elevated after exposure to noise. It is inferred that this elevation is caused by over-release of glutamate from hair cells and by reversal of the glutamate transporter.