急性次声波暴露后豚鼠位听功能及内耳超微结构的变化

目的观察次声波对豚鼠位听功能和内耳超微结构的影响。方法将豚鼠置于频率8Hz、声压级135dBSPL的次声声场中连续暴露90min。应用正弦摆动试验(sinusoidalpendulartest,SPT)、听性脑干反应（auditorybrainstemresponse，ABR）和畸变产物耳声发射(distortionproductionotoacousticemission，DPOAE)评价次声波暴露前后豚鼠前庭功能和听功能的变化，扫描电镜观察豚鼠内耳各结构表面超微形态的变化。结果次声波暴露后不同时间正弦摆动诱发的豚鼠前庭性眼震的最大慢相速度(slow-phasevelocity,SPV)和频率较次声暴露前轻微降低，但无显著性意义(P>0.05)。次声波暴露后各组动物ABR阈值较正常时略有升高，亦无统计学差异(P>0.05)，各组动物ABR各波潜伏期和波间期与次声暴露前比较差异均无显著性(P>0.05)；DPOAE的幅度值在各个频率段均有明显的降低(P<0.01)。扫描电镜下见各实验组动物内耳半规管壶腹嵴两囊斑及Corti器感觉毛细胞纤毛缺失、散乱、倒伏及融合，表皮板等结构均有不同程度的损伤。结论次声波对豚鼠前庭末梢感受器兴奋性可能有一过性的轻微抑制作用，但SPT无有意义改变。次声波可引起豚鼠内耳毛细胞超微结构的损伤，可导致豚鼠耳蜗外毛细胞功能明显减退，这种功能减退尚不足以引起听力的明显改变。

Effects of acute infrasound exposure on vestibular and auditory functions and the ultrastructural changes of inner ear in the guinea pig

Objective　To define the effects of acute infrasound exposure on vestibular and auditory functions and the ultrastuctural changes of inner ear in guinea pigs. Methods　The animals involved in the study were exposed to 8 Hz infrasound at 135dB SPL for 90 minutes in a reverberant chamber. The sinusoidal pendular test (SPT), auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAE) were respectively detected pre-exposure and at 0(within 2 hrs)、2 and 5 day after exposure. The ultrastructures of the inner ear were observed by scanning electron microscopy. Results　The slow-phase velocity and the frequency of the vestibular nystagmus elicited by sinusoidal pendular test （SPT）declined slightly following infrasound exposure, but the changes were not significant (P>0.05). No differences in the ABR thresholds, the latencies and the interval peak latencies of Ⅰ,Ⅲ,Ⅴ waves were found between the normal and the experimental groups, and among experimental groups. The amplitudes of DPOAE at any frequency declined remarkably in all experimental groups. The ultrastructures of the inner ear were damaged to different extent. Conclusion　Infrasound could transiently depress the excitability of the vestibular end-organs, decrease the function of OHC in the organ of Corti and cause damage to the inner ear of guinea pigs.