Cochlear damage in guinea pigs following contralateral sound stimulation with and without gentamicin.

The effect of a minimally damaging sound exposure and a sub-ototoxic dose of gentamicin on cochlear hair cells contralateral to the sound exposure was evaluated. The cochleae of pigmented guinea pigs exposed to an 8 kHz pure tone at 116 dB SPL for 1 h and/or 50 mg/kg/day of gentamicin for 10 consecutive days and repeated after an interval of 3 weeks, were used for this purpose. Hair cell loss was found to have occurred in the contralateral cochleae following the sound exposure alone. The occurrence of potentiation, synergism and differential synergism between the agents in the contralateral ears was also seen. Possible explanations for these phenomena are proposed.