The ototoxic effects of gentamicin on the vestibular maculae in pigmented guinea pigs.

The normal density of the sensory hair cells of the utricular macula in pigmented guinea pigs was examined. The central region had a greater sensory cell density than the peripheral region. The effect of three different doses of gentamicin on the sensory hair cells was quantified. An increase in sensory cell damage was found with increasing doses of gentamicin. A differential regional sensitivity occurred. The central region was more vulnerable to gentamicin than the periphery. Only the central region of the saccular macula was examined, but no sensory cell losses were found with any of the dose regimes used. The utricular macula is therefore more sensitive to gentamicin than the saccular macula. This work was compared with a similar study using albino guinea pigs, and it was found that the pigmented animals are probably more resistant to ototoxic damage.