An attempt was made to protect kanamycin ototoxicity by simultaneous application of heparin (HP), one of the strong polyanions. Mature guinea pigs with normal pinna reflexes were divided into three groups: control group, kanamycin (KM) group (200 mg/kg/day, i. m.) and KM plus HP group (0.5 orl U. /g/day, i. m.). The protective effect on ototoxicity was judged by pinna reflex, electrocochleography, cochlear microphonics and morphological investigation through SDH staining. A short term experiment with 23 times injections showed a protective effect of heparin against KM ototoxicity. However, a long term experiment with 50 times administrations revealed severer damages of the hair cells in the plus HP group than those in the group given only KM. These differences, however, were not statistically significant. In conclusion, HP can protect KM ototoxicity but the detoxication by KM-HP complex formation might be limited.
