Effect of Burow's solution on the guinea pig inner ear.
OBJECTIVE
We examined the changes in the inner ear hair cells following intratympanic injection of Burow's solution.


METHODS
Thirty-one albino guinea pigs with a normal Preyer's reflex were used. Burow's solution was applied and allowed to remain on the round window membrane for 30 minutes (30-minute group), 1 hour (1-hour group), or 2 hours (2-hour group). Seven days later, the left temporal bone was removed. Auditory brain stem responses were recorded at 4, 8, and 20 kHz before application of Burow's solution and again immediately before decapitation. The cochlea and utricle were dissected, stained with rhodamine-phalloidin, and examined under a fluorescence microscope.


RESULTS
The postoperative auditory brain stem response thresholds at 20 kHz in the 1-hour group and those at 8 and 20 kHz in the 2-hour group were increased significantly compared to the baseline thresholds. Surface preparations of the organ of Corti revealed no hair cell loss in the 30-minute group, loss of outer hair cells in the lower half of the basal turn in half of the animals in the 1-hour group, and loss of outer hair cells in the basal turn in almost all animals in the 2-hour group. In the 2-hour group, the microthin sections of the round window membrane showed degeneration of the outer epithelium.


CONCLUSIONS
The retention of Burow's solution on the round window membrane for 2 hours induces degeneration of the outer epithelium and damage to the cochlear outer hair cells.
Suzuki
Mitsuya
M
Department of Otolaryngology, University of Tokyo, Tokyo, Japan.
Kashio
Akinori
A
Sakamoto
Takashi
T
Yamasoba
Tatsuya
T
D000085:Acetates / Q000008:administration & dosage*; D000818:Animals; D016057:Evoked Potentials, Auditory, Brain Stem; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000187:drug effects*; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects; D007322:Instillation, Drug; D012405:Round Window, Ear / Q000187:drug effects; D013997:Time Factors; D014432:Tympanic Membrane
D000085:Acetates; C013396:aluminum acetate