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目的观察庆大霉素用药早期对听觉作用的不同机理。方法观察单次肌注庆大霉素（１２５ｍｇ／ｋｇ）前及用药后１５，３０，４５，６０，７５ｍｉｎ时，用短声（ｃｌｉｃｋ）和短音（ｔｏｎｅｐｉｐ）（８，４，２ｋＨｚ）刺激诱发ＣＡＰ，观察Ｎ１、Ｎ２振幅、潜伏期变化。结果短声刺激的ＣＡＰ阈值无明显改变，但Ｎ１波潜伏期随时间增加而逐渐延长；用短音刺激的ＣＡＰＮ１波潜伏期亦逐渐延长，但２ｋＨｚ短音刺激Ｎ１波潜伏期延长较缓慢。短声刺激的Ｎ１振幅随时间增加而呈下降趋势，８ｋＨｚ，４ｋＨｚ短音刺激ＣＡＰＮ１振幅呈一先上升后下降的趋势。短声和短音各频率组的ＣＡＰＮ１－Ｎ２间期随时间而延长。Ｎ２振幅无论是短声刺激还是短音刺激均呈下降趋势。结论早期应用庆大霉素可能有神经传导阻滞作用，其耳毒性作用不仅产生于感觉神经的终末端，也可能来源于中枢，这是可逆的，这种神经毒性作用也有频率特异性。
Objective To observe the different mechanisms of the effect of gentamicin on auditory function in the early stage. Methods The rats were treated with both click and tonepip (8,4,2kHz) before and at 15, 30, 45, 60 and 75 min after single intramuscular injection of gentamicin (125 mg / kg) Induced CAP, observed N1, N2 amplitude, latency changes. Results There was no significant change in the CAP threshold of short-sonic stimulation, but the latency of N1 wave gradually extended with the increase of time. The latency of CAPN1 wave stimulated by short tone was gradually prolonged, but the latency of N1 wave stimulated by 2kHz short tone was slower. The N1 amplitude of short-sonic stimulation decreased with the increase of time, and the amplitude of CAPN1 stimulated by short-tone at 8kHz and 4kHz tended to increase first and then decrease. The CAPN1-N2 interval in each frequency group of short and short sounds is prolonged with time. N2 amplitude either short-sound stimulation or short-tone stimulation showed a downward trend. Conclusions Gentamycin may have neurological blockade in early stage. The ototoxic effect may occur not only from the end of sensory nerve, but also from the central nervous system. It is reversible. The neurotoxicity is also frequency-specific.