STIMULUS-RELATED POTASSIUM CHANGES IN THE ORGAN OF CORTI OF GUINEA-PIG
STIMULUS-RELATED POTASSIUM CHANGES IN THE ORGAN OF CORTI OF GUINEA-PIG
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DOI：
10.1113/jphysiol.1989.sp017448
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发表时间：
1989-01-01
影响因子：
5.5
通讯作者：
SYKOVA, E
中科院分区：
文献类型：
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作者：
JOHNSTONE, BM;PATUZZI, R;SYKOVA, E
1.用双管钾离子选择性微电极测定豚鼠耳蜗头回Corti器内钾离子浓度。2.鼓阶电极穿透基底膜时，外淋巴液K+静息水平由3.0mmo1/L增加到皮质淋巴的3.4mmo1/L(n=8)。Corti器官胞外区K+静息水平差异不显著。在穿透角质板时，K+水平达到140mmo1/L，同时出现+80 mV的耳蜗内电位。毛细胞和支持细胞的刺入伴随着K+水平的增加，但没有系统地测量细胞内的K+水平。3.在500赫兹至25千赫的频率范围内，用纯音刺激可引起Corti器官K+水平的变化。这些变化的大小取决于刺激频率和强度。在高声强下，Corti隧道内K+浓度可增加1 mmo1/L，而与静息水平相比最大值增加3 mmo1/L靠近内毛细胞。4.在中等强度的短暂暴露中，纯音刺激(10 S，小于80dBSPL(声压级)，频率为4 kHz或更高)使Corti器细胞外液K+水平单调上升至一个稳定的峰值水平。停止刺激后，K+水平单调下降，时间常数约为2 S，接近刺激前水平。在某些情况下，这一水平略高于刺激前的水平。5.短时间暴露于中等强度声(10 S，<80dBSPL)时，Corti器细胞外电位呈正性。这种由声音引起的变化的幅度在刺激过程中调整到大约其初始值的五分之一。一旦刺激措施停止，潜在利率就会短暂跌破刺激前的水平，然后回升至刺激前的水平。这些变化的时间常数在2-3 S之间。6.状态良好的动物Corti器声诱发K~+水平升高的等速调谐曲线与已报道的初级传入纤维等速调谐曲线相似。
1. Potassium concentration was measured with double‐barrelled K+‐selective microelectrodes within the organ of Corti in the first turn of the guinea‐pig cochlea. 2. Penetration of the electrode from scala tympani through the basilar membrane was accompanied by an increase in K+ resting level from 3.0 mmol/l in perilymph to 3.4 mmol/l in cortilymph (n = 8). K+ resting level was not significantly different in various extracellular regions of the organ of Corti. On penetration of the cuticular plate, the K+ level reached 140 mmol/l simultaneously with the occurrence of a +80 mV endocochlear potential. Impalement of hair cells and supporting cells was accompanied by an increase in K+ level, but intracellular K+ level was not systematically measured. 3. Stimulation with pure tones over the frequency range 500 Hz to 25 kHz produced changes in the K+ level in the organ of Corti. The magnitude of these changes was dependent on stimulus frequency and intensity. At high sound intensities the K+ level in the tunnel of Corti could increase by typically 1 mmol/l, while a maximum increase of 3 mmol/l with respect to the resting level was observed immediately adjacent to inner hair cells. 4. During brief exposures to moderate intensity, pure tone acoustic stimulation (10 s, less than 80 dB SPL (sound pressure level] of frequency 4 kHz or greater the K+ level in the extracellular fluid of the organ of Corti rose monotonically to a steady peak level. On cessation of the stimulus the K+ level fell monotonically with a time constant of about 2 s to a level close to the pre‐stimulus level. In some cases this level was slightly above the pre‐stimulus level. 5. For brief exposures to moderate intensity sound (10 s, less than 80 dB SPL) the extracellular potential in the organ of Corti became more positive. The amplitude of this sound‐evoked change adapted during stimulation to a level approximately one‐fifth of its initial value. Upon cessation of the stimulus the potential fell transiently below its pre‐stimulus level, before recovering to that level. The time constant of these changes was between 2 and 3 s. 6. Iso‐response tuning curves for the sound‐evoked elevation in K+ level in the organ of Corti in animals in good condition were similar to iso‐rate tuning curves for primary afferent fibres reported previously.(ABSTRACT TRUNCATED AT 400 WORDS)