The ototoxicity of polyamino-compounds was exmined by means of perilymphatic perfusion, while monitoring cochlear microphonics (CM) as an indicator of ototoxicity. The selected polyamino-compounds were kanamycin, polymyxin B, poly-L-lysine, putrescine, and spermine; 10mM of each compound was perfused through the perilymphatic space, and ototoxicity was determined.
Polymyxin B and poly-L-lysine caused the disappearance of cochlear microphonic potentials (CM) within 15 min after the start of perfusion. Both putrescine and spermine caused moderate depression of CM, however; it was not so severe as that caused by kanamycin.
It was suggested that the ototoxicity of polymyxin B and poly-L-lysine was caused by their binding to the polyphosphoinositide receptor in much the same way kanamycin did. But the ototoxicities of putrescine and spermine did not seem to be concerned with polyphosphoinositide.
Further study is necessary to understand the mechanism of the ototoxicity of polyamino-compounds.
