缺氧豚鼠耳蜗总和电位和形态学实验观察

应用同一玻璃微电极在豚鼠中阶记录复合动作电位（ＣＡＰ）、总和电位（ＳＰ）和蜗内电位（ＥＰ），连续动态观察在缺氧、给氧过程中的变化，结合内、外毛细胞及突触形态学观察，发现缺氧时ＳＰ和ＥＰ幅度下降，极性发生改变。而ＳＰ极性及大小同时随ＣＡＰ阈值因氧供变化而变化。组织学检查结果内毛细胞琥珀酸脱氢酶无变化，外毛细胞琥珀酸脱氢酶活性下降，而突触内乙酰胆碱酯酶无变化。结果提示：在中阶记录的ＳＰ极性和振幅受ＥＰ     

对速尿引起总和电位与蜗内电位不同变化的认识

OBJECTIVE: To investigate the physiological properties of summating potential (SP) and to compare the different changes between SP and endocochlear potential (EP) induced by Furosemide in guinea pigs. METHODS: SP in response to clicks with alternative polarities at 105 dB peSPL was recorded from a electrode in the facial nerve canal. EP was measured with a glass microelectrode in the basal turn of the cochlea. SP and EP were observed simultaneously and continuously after injection of Furosemide or the solution of Furosemide-bovine serum albumin injected into the jugular vein of the animal. RESULTS: Before furosemide application, only SP could be recorded with small or without +SP. After furosemide injection, EP declined dramatically followed by reduction of the -SP which quickly vanished, while +SP appeared or the amplitude increased. When EP recovered to a certain level, +SP disappeared or dramatically decreased and then -SP reappeared. The amplitude of -SP increased progressively with EP recovery. Both -SP and EP recovered to the pre-injected level in 60 min after the furosemide application. CONCLUSION: The results suggest that Furosemide induced distinct changes of -SP and +SP, the two components of SP. The changes of -SP amplitude was consistent with that of the EP value, while the changes of +SP amplitude were contrary to that of the EP value.     

自适应滤波提取耳蜗微音器电位初探

为解决表面电极引导耳蜗微音器电位的结果中存在刺激伪迹信号的状况，探讨了用自适应滤波处理抵消刺激伪迹信号提取的方法，结果发现：正常耳的ＣＭ较同侧表面电极引导的波形有一定的滞后时间，２ｋＨｚ以上的神经动作电位波形分化明显；３１耳极重度感音神经性聋和１１耳中度或中重度感音神经性聋耳各频率的ＣＭ消失，９耳极重度感音神经性聋和２９中度和中重度感音神经性聋各频率存在较好的ＣＭ波形。提示：不同程度的感音神经性聋     

一氧化氮在豚鼠耳蜗作用的实验研究

为探讨ＮＯ在内耳的作用，采用外淋巴给药途径，观察一氧化氮气体（ＮＯ）、Ｌ－精氨酸、硝普钠及一氧化氮合酶（ＮＯＳ）拮抗剂Ｎ－甲基－Ｌ－精氨酸对耳蜗蜗内电位（ＥＰ）、复合动作电位（ＣＡＰ）及耳蜗微音器电位（ＣＭ）的影响。结果表明，Ｎ－甲基－Ｌ－精氨酸可以使ＥＰ减小５０％，ＣＡＰ振幅降低３３％及ＣＭ振幅略有降低，在此基础上，用Ｌ－精氨酸外淋巴灌流可以逆转Ｎ－甲基－Ｌ－精氨酸所致的改变。ＮＯ持外淋巴缓释能     

一氧化氮在豚鼠耳蜗作用的实验研究

为探讨ＮＯ在内耳的作用，采用外淋巴给药途径，观察一氧化氮气体（ＮＯ）、Ｌ－精氨酸、硝普钠及一氧化氮合酶（ＮＯＳ）拮抗剂Ｎ－甲基－Ｌ－精氨酸对耳蜗蜗内电位（ＥＰ）、复合动作电位（ＣＡＰ）及耳蜗微音器电位（ＣＭ）的影响。结果表明，Ｎ－甲基－Ｌ－精氨酸可以使ＥＰ减小５０％，ＣＡＰ振幅降低３３％及ＣＭ振幅略有降低，在此基础上，用Ｌ－精氨酸外淋巴灌流可以逆转Ｎ－甲基－Ｌ－精氨酸所致的改变。ＮＯ持续外淋巴缓释能使Ｎ－甲基－Ｌ－精氨酸导致的ＥＰ、ＣＡＰ及ＣＭ的改变恢复，并超过正常，随之出现快速下降。外淋巴灌流硝普钠后，ＥＰ、ＣＡＰ及ＣＭ短暂升高后逐渐下降，并维持在较低水平。ＣＡＰＮ１波及ＣＭ潜伏期的变化规律与其振幅的变化规律基本一致。结果提示，ＮＯ在生理条件下维持内耳功能，可能参与耳蜗毛细胞微机械特性及敏感性的调节，过量表达可以产生耳蜗毒性     

响度重振与耳蜗微音电位及耳聋预后的关系

目的了解响度重振与耳蜗微音电位(cochlear microphonic,CM)及耳聋预后之间的关系,探讨重振的形成机制.方法对104例一耳正常,另一耳为感音性听力下降并有响度重振的患者施行双耳CM测试,测试频率为0.5、1 kHz,以高频下降为主者加测2、4、8 kHz.将患者初诊时纯音听阈、双耳CM检测阈值与最终稳定之后的纯音听阈相比较,为便于分析结果,本文提出了CM分型标准Ⅰa型患耳CM检测阈值＜健耳,阈值差≤10dB;Ⅰb型双耳CM检测阈值相等,检测阈≤55dB SPL.Ⅱa型患耳CM检测阈值＞健耳,差值≥15dB SPL;Ⅱb型患耳检测阈值为60～75dBSPL.Ⅲ型患耳CM检测阈值＞75dB SPL或引导不出.结果听力正常组各频率CM绝对振幅在不同个体差异较大,但同一正常个体双耳之间CM幅值及阈值则较接近并稳定,因此不采用平均值而仅以同一个体正常一侧CM幅值的大小来评价患耳的CM幅值.重振耳CM有增大和延长现象.104例单侧感音性聋,95例(91.3%)主观检测有重振的频率出现CM振幅明显增大,其中34例在CM增大同时伴有CM延长(5.8%),与正常耳比较延长1～11个周波,平均时间延长(5.2±2.5)ms.初诊时即遵照CM分型标准分类,随后经6个月以上随诊,发现CM Ⅰ型预后明显好于Ⅱ型和Ⅲ型,Ⅰ型治疗总有效率高达78.19%;Ⅱ型多数预后不佳,治疗有效率仅为2.5%;Ⅲ型治疗均无效;将CM Ⅰ型与Ⅱ型做预后比较,组间差异具有显著性意义(x2=53.709,P＜0.001);Ⅰ型与Ⅲ型比较,差异亦具显著性意义(x2=21.444,P＜0.001);Ⅱ型与Ⅲ型比较,差异无显著性(x2=0.230,P＞0.05).睡眠状态下CM幅值略有增大,与此同时CM阈值减低.结论CM检测可为了解重振发生机理以及重振与CM和耳聋预后之间的关系提供可靠的客观信息.听力下降耳CM幅值正常或增大为重振所特有客观指征.     

对速尿引起总和电位与蜗内电位不同变化的认识

目的　研究SP的生理特性 ,探讨总和电位 (summatingpotential,SP)与蜗内电位(endocochlearpotential,EP)变化的关系。方法　实验使用 8只健康杂色豚鼠 ,经颈静脉注入速尿或速尿 小牛血清白蛋白混合液 ,同步观察SP与EP的改变。SP由 10 5dBpeSPL的交替极性短声诱发 ,面神经管电极记录 ;EP从耳蜗基底回记录。结果　用药前SP以 -SP为主 ,无 SP或很小 ,用药后随着EP的快速下降 ,-SP振幅迅速变小、消失 , SP出现或振幅增大 ;随着EP恢复到一定值 , SP消失或变的很小 ,-SP重新出现、振幅逐渐增大 ,60min时EP与 -SP均恢复至用药前水平。结论　速尿引起SP两种成分 -SP与 SP产生分离性改变 ,-SP振幅与EP幅值变化一致 ,而 SP振幅与EP幅值变化相反。     

Early morphological and chemical changes induced by cisplatin in the guinea pig organ of Corti

Guinea pigs were treated with a single dose of Cisplatin (5 mg IP). After 2-4 days the cochleas were prepared for morphological analysis by scanning electron microscopy and chemical analysis by X-ray dispersive microanalysis. Following Cisplatin, the bundles of stereocilia on the hair cells were found to be rough, disarrayed, fused, and finally absorbed. Significant increases were found in the levels of calcium, sulphur, and phosphorus in the abnormal hair cells. It is suggested that the high calcium levels might be due to the inhibition of enzymes which normally keep cytoplasmic calcium low, and that some of the changes in the stereocilia might be secondary to this.     

连翘酯苷对顺铂作用后豚鼠耳蜗c-jun表达的影响

目的：研究连翘酯苷对顺铂作用后豚鼠耳蜗c—jun表达的影响。方法：将30只豚鼠随机分为对照组（10只）,顺铂组（10只）和连翘酯苷组（10只）。腹腔注射顺铂溶液（8mg／kg）,1次／d,连续7d,建立顺铂耳毒性模型;连翘酯苷组在每次注射顺铂溶液30rnin前腹腔注射连翘酯苷25．0mg／kg／d,连续7d;对照组以生理盐水代替顺铂溶液注射,连续7d。实验动物被处死前,检测其DPOAE幅值变化;采用蛋白质印迹杂交（Western Blotting）检测各组豚鼠耳蜗c—jun蛋白的表达,逆转录聚合酶链反应检测各组豚鼠耳蜗c—jun基因mRNA的表达。结果：顺铂组DPOAE幅值明显低于对照组（P〈0．01）;相比于顺铂组,连翘酯苷组DPOAE幅值明显升高（P〈0．05）。顺铂组豚鼠耳蜗c—jun蛋白与mRNA表达水平均显著高于对照组（P〈0．01）;相比于顺铂组,连翘酯苷组C-jun蛋白与mRNA表达水平明显降低（P〈0．05）。结论：连翘酯苷能够通过降低c—jun的表达防护顺铂所致的耳蜗损伤。     

Physiological and morphological characterization of efferent neurones in the guinea pig cochlea

Efferent neurones within the intraganglionic spiral bundle of the guinea pig cochlea were characterized in terms of their response properties, and their pattern of termination within the receptor organ revealed by intracellular labelling with horseradish peroxidase. All neurones subsequently identified as efferent neurones had clear features of their response properties which distinguished them from primary auditory afferents. They had long latency, low maximum discharge rate and low levels of spontaneous activity under Nembutal/Innovar anaesthesia. The pattern of discharge was extremely regular, revealed by symmetrical interspike interval histograms. 49.4% responded best to ipsilateral, 43.3% to contralateral sound and a third group of 7.3% responded equally well to either ipsilateral or contralateral sound. In cochleae in good physiological condition, these efferents were as sensitive and as sharply tuned as primary afferents with the same characteristic frequencies (CFs). All efferents fully traced in histological processing terminated on the outer hair cells. Several efferents showed extensive branching beneath the inner hair cells which might represent en passant synapses with other neuronal elements. There was clear evidence of tonotopic organization of the efferent projection. The site of termination on the outer hair cells in most instances was very close to the region of the cochlea predicted from the fibres' CF and the known place-frequency map for primary afferent neurones in the guinea pig.     

Cytochalasin D suppresses sound evoked potentials in the guinea pig cochlea

Cytochalasin D (CD), an inhibitor of actin polymerization, was perfused through the guinea pig cochlea while monitoring various cochlear potentials. CD (10(-7)-10(-5) M) reduced the magnitude of the compound action potential of the cochlear nerve and the summating potential, and increased N1 latency. The cochlear microphonic potential was the least sensitive potential with only a slight effect being observed at 10(-5) M. The results are consistent with the hypothesis that actin has a role in cochlear function.     

Endocochlear potential in focal lesions of the guinea pig cochlea

To estimate the correlation between the cochlear lateral wall and endocochlear potential (EP), the EP was measured at different time intervals up to 3 weeks at cochlear focal lesions made in the guinea pig. Lesions were produced by a photochemical reaction between systemically administered Rose Bengal and green light illumination in the second cochlear turn. Focal strial lesions (mean diameter 975 microm) became apparent under a scanning electron microscope 60 min after illumination, and degeneration of the organ of Corti was recognized at 3 days. The EP was measured continuously for 1 h following onset of the reaction in eight ears. In the other ears, EP measurements were done after various intervals of time up to 3 weeks. The EP showed two declines from pre-illumination level. The first started soon after illumination, reached a minimum value at 25 min, and then slightly recovered by 1 h. The second decline appeared at 3 days after illumination. In contrast to evident focal morphological degeneration 2 weeks post illumination, the EP values had recovered to almost normal. We suggest that the sequential changes in the EP were produced depending on the degeneration and then repairing processes of the endolymphatic boundary tissues.     

豚鼠耳蜗局灶性微循环障碍模型的建立

目的 :探讨耳蜗局灶性微循环障碍对耳蜗血流、听功能及耳蜗形态学的影响。方法 :采用光化学诱导法 ,经豚鼠颈外静脉注射 2 %四碘四氯荧光素二钠 (RB)后 ,用 (5 4 0± 4 0 )nm的绿色光照射耳蜗第 2转外侧壁(范围约 1.2mm× 1.0mm) ,诱导该部位血管纹微血栓形成。结果 :诱导后观察 5h ,被照射部位的耳蜗血流随时间逐渐下降 ,动作电位阈移值逐渐提高 ,二者的变化呈负相关。耳蜗铺片显示 ,被照射部位诱导后 30min耳蜗外侧壁毛细血管扩张 ,部分毛细血管轮廓不清、血流中断 ;诱导后 90～ 30 0min ,大片的毛细血管萎缩、闭塞、数目减少 ;诱导 3h后 ,光照区内部分外毛细胞、内毛细胞坏死缺失 ,外毛细胞病变较内毛细胞为重 ,毛细胞坏死区的长度为 (115 2 .5 0± 36 3.2 6 ) μm(n =4 )。非光照区CBF及形态学均无明显变化。结论 :光化学法可诱导耳蜗外侧壁局限性微血管损伤 ,造成豚鼠听力下降 ,为耳蜗不同部位微循环障碍导致不同类型听力损伤的研究提供了实验依据 ,并为耳蜗血栓性疾病探索新的治疗方法提供了动物模型。     

Development of morphological and physiological changes in the cochlea induced by cytomegalovirus

The effect of viral infection in the cochlea was investigated by inoculation of live cytomegalovirus or inactivated virus. Auditory thresholds were measured on the day of inoculation and on the terminal day. Two to 8 days following inoculation, the animals were killed and the cochleas were evaluated histologically. The compound nerve potential showed an increase in threshold prior to the cochlear microphonic, indicating the nerve was affected prior to the outer hair cells. All experimental cochleas contained inflammatory and cytomegalic inclusion cells and showed degenerative changes. The number of infected cells was small relative to the histopathology. Control cochleas had normal structure and function. The degeneration, therefore, might be mediated by inflammation as well as by the cytopathic effect of the virus. Viral infections, therefore, might be better managed with anti-inflammatory therapy in addition to antiviral agents.