1993 Volume 1993 Issue Supplement68 Pages 1-8
This study investigated whether decreased endocochlear potential (EP) influences susceptibility to acoustic trauma. Guinea pigs with decreased EP following i. v. administra- tion of furosemide (FUR) and control animals with normal EP were exposed to 2 kHz pure tone ranging from 115 to 130 dB SPL for 5 min. The input-output curves of the compound action potential (CAP) before acoustic overstimulation were compared with those 2 hours after the exposure. With 125 and 130 dB SPL exposure, there was no significant difference in the threshold shift between the FUR and the control groups. With 115 and 120 dB SPL exposures, however, the threshold shift of the FUR group was significantly smaller than that of the control group. These results indicated that the threshold shift of CAP is mainly due to excessive vibration of the basilar membrane in the greater stimulus groups (125∼130 dB SPL), but energy exhaustion of the hair cells participates in the threshold shift to a certain extent when the stimulus is milder (115∼120 dB SPL). It was concluded that susceptibility to acoustic trauma from a milder intensity (115∼120 dB SPL) was reduced, when the energy consumption rate of the organ of Corti was decreased by EP suppression.
