Interaction of polyanion against kanamycin ototoxicity.

We studied whether interference of the electron bindings between kanamycin (KM) and the outer plasma membranes of the hair cells with polyanion such as heparin can reduce ototoxicity. In a short course experiment, KM 200 mg/kg/day was injected intramuscularly 23 times with or without 1 U or 0.5 U of heparin/g/day differently to 22 guinea pigs. The reducing effect of heparin against KM ototoxicity was significant from a comparison of the N1 threshold obtained by the cochleogram. The number of surviving outer hair cells in the heparin groups was significantly greater in the third turn than in the group given KM alone. A long course experiment in which 50 injections of KM with or without 0.5 U of heparin were given intramuscularly to 16 guinea pigs revealed from the pinna reflex, cochlear microphonics and cell counting that heparin could reduce ototoxicity slightly at an early stage or before reaching crucial accumulation.