Combined effects of adrenalectomy and noise exposure on compound action potentials, endocochlear potentials and endolymphatic potassium concentrations

• Published in: Hearing research 1995-11, Vol.91 (1), p.79-86
• Main Authors: Ma, Yi Long, Gerhardt, Kenneth J., Curtis, Lisa M., Rybak, Leonard P., Whitworth, Craig, Rarey, Kyle E.
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation; Action Potentials - physiology; Adrenalectomy; Adrenalectomy - adverse effects; Analysis of Variance; Animals; Auditory Threshold - physiology; Biological and medical sciences; Cochlea - physiology; Cochlear Microphonic Potentials - physiology; Compound action potential; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Endocochlear potential; Endolymph - metabolism; Fundamental and applied biological sciences. Psychology; Microelectrodes; Noise exposure; Potassium; Potassium - metabolism; Random Allocation; Rats; Vertebrates: nervous system and sense organs
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/0378-5955(95)00172-7

The effects of removal of endogenous corticosteroids via bilateral adrenalectomy in combination with noise exposure (30 min at 100 dB) were determined by recording compound action potentials (CAP) and endocochlear potentials EP), and by measuring potassium concentrations (K e +) within the endolymph. Thirty-eight Long-Evans rats were divided into groups according to experimental treatments: adrenalectomy (ADX) or non-ADX and noise exposure or non-noise exposure. CAP thresholds, EP and K e + values were subjected to repeated-measures analysis of variance with group and time as factors classifying the measurements. Noise exposure resulted in significant elevations of CAP thresholds in both the ADX and non-ADX animals, but had no effect on either EP or endolymphatic K e +. Recovery was noted during all post-exposure measurement periods and was significantly faster to ADX animals. EP and K 3 + did not change during or after noise exposure. ADX animals showed a non-significant reduction of EP and a statistically significant increase of K e + during all measurement periods as compared to non-ADX animals.